As a specialty contractor to AECOM, Accura was selected to provide geotechnical services to obtain general descriptions of the area subsurface soil, rock, and groundwater conditions within the crest area and downstream toe of the dam. Additionally, field testing, obtaining laboratory tests, and preparation of a geotechnical report were accomplished. Twin Brothers Lake/Dam is located at about 550 feet northeast intersection between Toronto Trail and Canadian Way in Tucker, DeKalb County, Georgia. The dam and lake are surrounded by wooded area, dense residential properties, Stapp Drive, Toronto Trail, and Canadian Way. the Twin Brothers Lake Dam was constructed more than 60 years ago to create a small lake for fishing. The end purpose of the project is to rehabilitate and improve the dam to bring it into compliance with the requirements of Georgia Safe Dams Program.
The earthen downstream slope of the dam is heavily vegetated, to include hardwoods that range to about 24-inches diameter. Due to these conditions, boring locations were hand cleared for the drilling rig. Standard Penetration Testing (SPT) and split-spoon soil samples were obtained in the soil test borings at designated intervals in general compliance with ASTM standards. Split-spoon samples were sent to the laboratory for classification and boring log preparation.
Accura prepared a written geotechnical data report for the project summarizing our work on the project, providing descriptions of the subsurface conditions encountered, laboratory testing program, visual classifications will be in accordance with USCS and classifications will be adjusted based on the results of the laboratory testing, logs of all borings should delineate the limits of stratum encountered (Fill and Embankment materials, Residuum, Saprolite, Partially Weathered Rock, etc.), and the results of all field and laboratory testing for the design team and the planned construction. All work was completed under the direct supervision of a registered professional geotechnical engineer.