Phase I Archaeological Survey of the Proposed Islands Expressway (CR787) Bridge Replacements Project Corridor

Between December 13 and 14, 2010, Brockington and Associates, Inc., conducted an intensive Phase I archaeological survey of the proposed Islands Expressway (CR787) Bridge Replacements project corridor in Chatham County, Georgia (GDOT Project CSBRG-0007-00 [128]; PI 0007128; HP-110113-003). This project represents the construction of two new, high level, fixed span, multi-lane bridges over the Wilmington River (Atlantic Intracoastal Waterway). The proposed project would replace the functionally obsolete double bascule bridges. The proposed project would begin at a point approximately 0.6 mile (0.9 kilometer) west of the Wilmington River centerline and extend eastward to a point approximately 0.6 mile (0.9 kilometer) east of the Wilmington River centerline. Total project length would be approximately 1.2 miles (1.9 kilometers). The portion of the corridor located in the Wilmington River itself was subject to an underwater archaeological survey by Tidewater Atlantic Research, Inc. of Wilmington, North Carolina, and is discussed in a separate report (Watts 2011) provided in Appendix B.

Likewise, an architectural survey of the project corridor is detailed in a separate report. The terrestrial archaeological survey was conducted along the land portion of the project corridor, located on either side of the Wilmington River, 0.33 miles (0.5 kilometer) east of the city limits of Savannah, Georgia. For this project, the Area of Potential Effect (APE) consists of the existing project right-of-way-of-way (ROW) and proposed construction easements within which all ground disturbing activity is confined. The APE begins at a point on the Islands Expressway approximately 0.6 mile (0.9 kilometer) west of the Wilmington River centerline and extends eastward to a point approximately 0.6 mile (0.5 kilometer) east of the Wilmington River centerline. The width of the APE extends approximately 100 feet (30.5 feet) north and 100 feet (30.5 feet) south of the existing pavement of the Islands Expressway. The archaeological survey was conducted within the APE as well as within an additional 100-foot (30.5 meter)- wide buffer zone beyond the APE on both the north and south sides of the project corridor. The buffer zone was surveyed to account for corridor alignment shifts and intersection design refinements.

Survey investigations were carried out on behalf of the LPA Group Incorporated, a Unit of the Michael Baker Corporation, in compliance with Section 106 of the National Historic Preservation Act (NHPA) of 1966 (as amended) and the Advisory Council on Historic Preservation revised 36 CFR Part 800 Regulations by personnel qualified under 36 CFR Part 61. Background research and archaeological field survey were used to identify potentially significant archaeological resources within the project’s APE and buffer zone and to evaluate their eligibly for listing on the National Register of Historic Places (NRHP).

Background research consisted of an examination of archaeological site forms for previously recorded sites, historic resource survey files, and reports for previous cultural resources investigations conducted in the vicinity of the project corridor. In addition, files were reviewed to determine whether NRHP listed properties are located within or near the project area. The investigated records are maintained by the Georgia Archaeological Site File (GASF) at the University of Georgia in Athens, and the Georgia Historic Preservation Division (HPD) in Atlanta. This data set is also available online through the Georgia Natural, Archaeological, and Historic Resources Geographic Information System (GNAHRGIS). Background research was also conducted at the University of Georgia Map Library in Athens, Georgia and the Georgia Historical Society in Savannah.

Background research identified one archaeological site, 9CH759 (Fort Bartow), which is located within the APE, immediately north of the project corridor. Fort Bartow is a large Civil War period earthwork remnant and is a recommended eligible for the NRHP. Seventeen other previously recorded archaeological sites are located within a one-mile radius of the proposed project corridor, but are outside the APE.

The terrestrial archaeological field survey did not identify any additional archaeological sites or isolated finds. However, the previously recorded archaeological site 9CH759 was re-visited. The field survey documented the location of the southern end of 9CH759 as within the 100-foot-wide buffer area for the project corridor, but outside the existing ROW and proposed construction easements. We recommend avoidance of this site and that any modifications to the proposed plans avoid 9CH759. If avoidance is not possible, then we recommend a mitigation plan be developed which would include testing or data recovery of the portion of 9CH759 that would be affected.

In conjunction with the terrestrial archaeological survey, Brockington and Associates, Inc., requested that Tidewater Atlantic Research, Inc., (TAR) of Washington, North Carolina, conduct the river portion of the survey for the proposed project area. In order to determine the proposed project’s effects on potentially significant submerged cultural resources, TAR conducted a magnetometer and side-scan sonar survey of the proposed project area. Field research for the project was conducted on January 13, 2011. Analysis of the remote-sensing data generated during the survey identified a total of 28 magnetic anomalies. One of the magnetic anomalies had an associated acoustic signature indicative of a crab trap. Sixteen individual anomalies represent small single objects that appear to be modern debris such as fish and crab traps, pipes, small diameter rods, cable, wire rope, chain, small boat anchors. Two acoustic targets are indicative of pilings and modern debris. No additional investigation of those anomalies is recommended in conjunction with the proposed project. Four anomaly clusters, composed of 11 magnetic anomalies and one acoustic target, have signature characteristics consistent with shipwreck material and/or other potentially significant submerged cultural resources. These clusters are formed by spatially associated anomalies and are recommended for avoidance. Three clusters, WR-1, WE-2 and WE-4 should be protected by the creation of 75-foot radius buffer zones and cluster WR-3 by a 50-foot radius buffer zone. Should avoidance prove impossible, additional investigation is recommended to identify the material generating the buffered anomalies and assess historical significance in terms of National Register of Historic Places (NRHP) eligibility. If the buffered anomalies are avoided, proposed project construction will have no impact on submerged cultural resources. The detailed results of the underwater investigations are provided in a full report (Watts 2011) in Appendix B.