Columbus progress

摘要

Breakthrough of the 14ft (4.2m) diameter Lovat EPBM on 1 August marked the end of delay-ridden operation by McNally/Kiewit JV on the Part 2 Big Walnut Outfall Augmentation Sewer (BWOAS) contract in Columbus, Ohio. The 13,240ft (4.2km) long segmentally lined tunnel through predominantly glacial-till and glacio-fluvial deposits took a total 24 months to complete. The best production week was in June 2007 with 79 rings or 390ft (119m) completed in the best mining and ring-building times of 8 and 17 minutes respectively.