Phase I Archaeological Resource Survey of the Proposed Bridge Replacement at State Route 78/ U.S. Highway 221 Over Williamson Swamp Creek Jefferson County, Georgia; GDOT PI No.: 0015554; HP # 180919-004

Between January 14-19 and February 4-6, 2019 HNTB completed a Phase I archaeological survey for the proposed bridge replacement at State Route (SR) 78 / U.S. Highway (US) 221 over Williamson Swamp Creek in Jefferson County, Georgia. This survey was conducted for the Georgia Department of Transportation (GDOT), PI Number 0015554, to assist GDOT in complying with Section 106 of the National Historic Preservation Act (NHPA).

The existing bridge on SR 78/US 221 over Williamson Swamp Creek (Structure ID 163-0023-0) was constructed in I 946 and widened in I 982. The existing bridge consists of 20 continuous steel beams on concrete caps with steel piles in the original section and concrete caps with concrete piles in the widened section. The bridge was designed to accommodate an H-15 vehicle, which is below current design standards. A structure analysis shows a lower than expected carrying capacity in the substructure of this bridge. Due to the structural integrity of the bridge pertaining to the design vehicle, the structural analysis of the structure, and the unknown foundation of the substructure, replacement of this 73-year-old bridge was recommended by GDOT. Existing right-of-way (ROW) along SR 78/US 221 varies from 75 feet wide (ft) to 150 ft wide. Existing ROW along SR 242 is 120 ft wide. Proposed ROW would vary with permanent easements anticipated. A temporary detour bridge on the east side of SR 78/US 221 over Williamson Swamp Creek is anticipated during construction.

For PI Number 0015554, the archaeological survey area included all areas within an Environmental Survey Boundary (ESB). The ESB is anticipated to encompass all possible/foreseeable ground disturbance activities and was generated by the GDOT project Designer in March 2018. In accordance with Section 106 of the NHPA, the area of potential effects (APE) is the geographic area or areas within which an undertaking may directly or indirectly cause alterations in the character or use of historic properties, if any such properties exist (36 CFR800.16[ d]). When design is complete, the project APE will likely be smaller than the ESB that is shown and evaluated herein. The width of the ESB along SR 78/US 221 is 360 ft wide expanding to 410 ft wide at Williamson Swamp Creek. The width of the ESB along SR 242 is 300 ft wide. The ESB along SR 78/US 221 begins approximately 1,025 ft (3 I 2 meters [m]) south of the SR 242 and SR 78/US 221 intersection and extends northeastward approximately 2,480 ft (756 m), terminating at the Shop Street/Back Street intersection with SR 78/US 221. The ESB along SR 242 extends approximately 530 ft (162 m) northwest of its intersection with SR 78/US 221. The ESB comprises approximately 25 acres. Five archaeological sites and one isolated find were recorded.