The Total Barrier Oxidation Ditch (TBOD), a recent development in oxidation ditch technology is described. The study was carried out in 1986 and 1987 for the purposes of: (1) evaluating the applicability of selected test procedures developed by the American Society of Civil Engineers (ASCE) Committee on Oxygen Transfer for estimating oxygen transfer of a circulating oval aeration basin, as represented by the TBOD configuration; and (2) generating reliable clean and process water oxygen transfer data on two TBOD's at Opelika, Alabama, and South Hill, Virginia. The methods used in the clean water test program included the ASCE nonsteady state procedure, the krypton/tritium radiotracer procedure, and a technique in which a dissolved oxygen mass balance is performed across the aeration device. In the process water test program, methods utilized included off-gas analysis and the above radiotracer procedure at both sites plus a process oxygen consumption/oxygen supply mass balance at one of the sites.