[en] This document contains the results of a geophysical investigation of nine Group II sites: (1) 116-D-7 and 116-DR-9 Retention Basins (2) 116-DR- 1 and 116-DR-2 Liquid Effluent Trenches (3) 107-D-1, 107-D-2, 107-D-3, 107-D-4, and 107-D-5 Sludge trenches. All nine sites were directly associated with the operation of the retention basins which are located in the 100-DR-1 Operable Unit. An area south of 116-D-7 was also investigated as an area that may have contained buried debris. The objectives of this investigation include the following: (1) Locate, map, and/or verify locations of subsurface pipelines and utilities. (2) Locate and map five sludge disposal trenches. (3) Map the extent of 116-DR-1 and 116-DR-2 liquid disposal trenches. (4) Locate and accurately map any unknown features (e.g., major concentration of debris, pipelines, and utilities) that could be a factor during subsurface remediation work