TRIAL SHAFTS

Evening Post, Volume CXXII, Issue 69, 18 September 1936, Page 11

TRIAL SHAFTS

LIBRARY BUILDING SEA BED AT FIFTEEN FEET The sinking of trial bores and shafts over the site ~of the new Central Library has now been,, carried- sufficiently far to give : the guidance necessary for the preparation of the final plans for the foundations of the building. The site is wholly of, reclaimed grojind and until the bores were made there was no certainty as to the depth at which solid ground would be found, or whether ithe' old sea bottom would be in any degree regular or: uneven.

The investigations, have shown the conditions to be rather better than was expected in that the sea; bottom is at an even depth of-about fifteen feet, though the depth at which really solid ground is found.is too deep; for standard pile foundations, ■ for piles would drive arid go on driving easily and expensively. ' ; '/'■"-■' However, no difficulty is anticipated, for the building will be carried on a series of heavy and: as the floor of the basement will be below ground level and will be constructed- over the whole library' area in reinforced concrete it will act as a raft foundation.

Water is met at a depth of about seven feet "in the' shafts," that is. at about high-tide level,- for the filling of the reclaimed areas,' 'though • well consolidated after many years, is still, open enough to be saturated to tide level. The necessity of fighting back water seepage while foundations are being laid or basements constructed is well known to Wellington -builders, and is not going to present any unusual difficulty in the casei-of the new library."