AUCKLAND WHARVES.

Auckland Star, Volume LVI, Issue 29, 4 February 1925, Page 15

AUCKLAND WHARVES.

CONSTRUCTION OF RETAINING WALLS. HEri'irr uv actixo exgixf.eu. A rc|iurl ,m tin. construction of retaining wall* on the Auckland xvalerfronl xvas submit tod to tho Harbour Board yesterday afternoon liv the netingcnginoor. .Mr. I). Holilerness.' T!». ijiiav Street xvall— Queen's xvharf to th.' N'nrtlii'rii wharf it xvas explained, xvas built in 188(1 lor tho Railxviiy Department to plans prepared by tho Public Works Department for the purpose oi reclaiming an area from tho sou for tlio Minion turd and xvatcrfront run.l. The roporl continued: "li- i.instruction took tho form of a. gravity masonry xvall from loxv xvatcr upwards built on'a concrete foundation, which in nun xvas standing ii]>on scoria in .1 tronrli incased between two rows of shoot piling, and dredged either to Took or still' blue ,-hiy. "There would appear to have been an extrni.rdin.irv lark of co-operation between tin- l.'ovennnent Departments and the Board, in that whilst, the Board had every intention of dredging in front of this wall su us to make „«. n f it a.s a berthage and had apparently made known its intention to tbe Public Works Department lie fore the design xvas prepared, tho xva.ll was built in such a manner that it must obviously bo unstable after any appreciable amount of dredging had boon carried out ill front. "I nfortunately the plans xx-ere not fubmittnl to the Board for its approval or comment, when the Board had carried out a certain amount of dredging in front of tbe newly constructed wall in pursuance or its prearranged plans, the instability of the xvall under altered conditions xvas quickly demonstrated so that in lSS.it', on ilie advice of (he then Engineer. Mr. D. E. lle.Donald, supported by the late Mr. Ware, remedial measures had to Tie adopted over a length of the xvall in its deepest 6eelion adjacent to the Queen's wharf. "These took the form of heavy concrete buttresses sunk to the hard bottom against tho face of the wall, and a heavy rubble bank deposited in dredged trenches between the buttresses. During the construction of the first of these, a short length of the xvall actually collapsed, and this portion xvas rebuilt as part of the buttress. The section of the wall treated as above xvas thereby Tendered completely stable, which is evidenced by the fact that it has gix-cn no further trouble during nearly 40 years which has elapsed sinceits completion. "In 180R it xvns found necessary to similarly buttress a further section of .be wall. Since that date no further movement has taken place in any part of the xvall, nor have any additional safeguards been necessar}'.'' Regarding the Prince's xvharf. it was stated "that for a distance of 100 feet on tbe western approach to Prince's wharf, it xx-as necessary to dredge away a. portion of the old solid filling forming the inner end of Hobson wharf, as the nexv lino of wharf came inside the thru existing face of Hobson wharf, and also in order to provide the required depth of wafer in the berth at the nexv xvharf. This involved dredging out part of the long deposited stone bank xvhich had formed a part of Hobson xvharf. After dredging, a rubble mound xvas again deposited in a suitable position among the piles of Prince's wharf and a concrete xxall built thereon. This xvall xvas to have been built well clear of tbe piles, but owing to one of the piles being about ten inches out of line, tbe wall at this point xvas inadvertently alloxved to come in contact with the pile. "Tho natural settlement of the bank caused the xvall to press against the pile and dainnge it. "After steps had been taken to prexent further movement by building up the bank against tbe face of the xvall xvith concrete bag xvork, the pressure xvas relieved from behind the pile xvhich noxv stands clear of the xvall. "There are in all 2252 piles in Prince's wharf. "The remainder of the reclamation xvall at Prince's xvharf is built on rubble mounds deposited on level bottom, and not in any xvay on sidelong ground. "It is, hoxvever, desirable even in this case to protect the face of the bank against erosion by xvax-e action, and it is proposed to take advantage of loxv spring tides to carry out this work as opportunity offers." The Calliope dock and Sheerleg's wharf xvas reported to have been built in l!)0ii-9 to plans and conditions approxed by, the Admiralty. "Beyond occasional minor damage to waitings, etc., due to collisions, xvhieli have been repaired from time to time, this structure has xvithstood the passage of 1(5 years in a remarkable manner, and the expenditure of a few hundred pounds in removing slight rust spots, which are unax-oidable in any work of this magnitude and to which no importance is attached. would place this wharf in a condition equal to nexv."