Annual Report of the Metropolitan Water and Sewerage Board Volume 2 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1903 edition. Excerpt: ...it always near the end of the work. Owing to the difficulty of placing the invert while the other work is in progress, this portion of the lining is omitted until the excavation is completed or until it becomes necessary. At the end of the year the tunnel lining had a total length of 375 feet. For eight weeks in the latter part of the year the average total weekly progress of the excavation for both ends of the tunnel was 21 feet of full section. Excavation is suspended while the masonry is building, which in part accounts for the low rate of progress. At the end of the year 305 linear feet remained to be excavated. Tunnel No. 2, which is 3,015 feet long, was excavated wholly through granite and diorite formations. At the beginning of the year the excavation of the tunnel at its easterly end was in progress, and excavation was begun at the westerly portal on January 20. As already stated, this tunnel was excavated for substantially its full length at the end of the year, as the headings were within 5 feet of the meeting point. None of the masonry lining has as yet been built. Tunnel No. 3, which is 2,160 feet long, was excavated for the greater part of its length through granite and diorite formations, though for about 125 feet near the easterly end and about 50 feet near the centre of the tunnel the surface of the ledge was below the top, and the overlying earth required to be supported by timbering. At the beginning of the year the excavation of the tunnel at its westerly end was in progress, but at the easterly end the excavation of the portal cut did not reach a point where the tunnel could be begun until February 20. The heading at this point was barely started when a thaw and heavy rains caused the sides of the portal cut to slip, ..