Dagama dam is an earthfill/gravity-type dam on the Witwaters River. It was built in 1971, is used for irrigation and has a capacity of 13 578 000 m³. The dam wall is spectacular when it is overflowing.
This is a two-stage puzzle. Firstly, work out the final co-ordinates from the sudoku puzzle below. Then work out how to sign the log sheet.
Thanks to Bouts777 for the original cache located near here.