Overdepth Dredging and Characterization Depth Recommendations

PURPOSE: This technical note (TN) describes the excavation accuracy of various dredges under different project conditions, and provides guidance to U.S. Army Corps of Engineers (USACE) personnel in determining depths to adequately characterize and evaluate material to be dredged in the entire dredging prism, including paid allowable overdepth and non-pay dredging. The technical note also improves communication on these subjects with other agencies and the public. Proper selection of characterization depths, considering the dredge's excavating accuracy and respective project-specific conditions, is critical to ensure future compatibility of the dredging description and quantities in environmental compliance documentation with the dredging as actually implemented. This guidance is meant to supplement Engineer Regulation (ER) 1130-2-520 (USACE 1996) and the Memorandum for Commanders, Major Subordinate Commands, Assuring the Adequacy of Environmental Documentation for Construction and Maintenance Dredging of Federal Navigation Projects (USACE 2006). Much of the information from the USACE 17 Jan 2006 Memorandum is included in this technical note. The original document contains color images.