ANOTHER SUB-STATION

Evening Post, Volume CXX, Issue 7, 8 July 1935, Page 11

ANOTHER SUB-STATION

CONSTRUCTION PROBLEM

HOLDING A BUILDING UP,

Mainly as the direct result, of the erection of two large jnsuranpe buildings in Lambton Quay and Customhouse Quay, the pending construction of the new Commercial Bank building, and a third big insurance building in. Featherston Street, as well as the steady development, of that section ot the city in the few years since the electrical power distribution system was modernised at the time of the change-over to the higher voltage, it has become necessary to; establish a third electrical sub-station in the midcity area and there are points of quite unusual interest about the work. There are at present .sub-stations in Featherston Street, a few blocks north of the Post Office, and in Chews Lane, off Willis Street, but the demand for power in this limited. area is such today with the load by no means fully developed that further; provision is eSln n these -. sub-stations are housed transformers, -which..receive power at 11000 volts and transform it down to standard voltage, switch gear, and various controls. They do not occupy any great space/but in that part of the city even a small space is hard to come by. Several possible sites were considered, one was a vacant piece of. land m Featherston Street, others were m the basements of buildings in/ithe. course of erection, and the. possibilities of rebuilding the public convenience at tee corner of Featherston Street and.Lambton Quay and construction of the substation above the ground level were discussed. Finally an agreement was reached between the City Council and the owners of Nathan's Buildings foi a long lease of a basement under the Featherston Street frontage ■. but with the site-found, extraordinary construction difficulties had to be>overcome. CUTTING THE FOUNDATIONS. To obtain the necessary, headroom for the equipment the basement' had to be deepened and also to be lengthened to give more floor space. It was necessary, therefore, to lengthen the main foundation piers and to.relocate dividing walls, and this meant that the full weight of the five-storeyed building had to be temporarily carried while new . supporting piers were being put in. This was done by rivet* ing brackets to either side of the c* uosed steel of the three piers involve* and the placing of; straddling piers which took the weight while the foundation pier was cut out and the bioad concrete footing drilled away, to allow the replacement steel to be set in position It is estimated that the temporary supports carried about 100 tons, the piers being taken out and replaced in turn. At the same time thejfootings were tied together in accordance with the new requirements is to earthquake safety, and. the. basement was made thoroughly waterproof, bottom and sides, to a height above the seepage level of the reclaimed area. As the 11,000-volt mains, run up Featherston Street the lengths required to connect up the new sub-station are short and the low-voltage lines are also reached across the roadway.For the present, equipment to handle 1500 k w. is being installed, but there is space for adaditional equipment to 2000 k.w. or more, and to provide for the bringing in of additional cables, ducts in excess of those which will at once be needed are being laid under the roadway. ' ;