STONE FOR BREAKWATER.

Gisborne Times, Volume LIX, Issue 9577, 31 July 1923, Page 3

STONE FOR BREAKWATER.

HAH BOR ENGINEER'S REPORT. QUARRY AT RAKAUROA •’RECOAIAI ENDED. The position in regard to the Engineer's investigations in to :-rioiw deposits for .harbor construction was covered by a very full report presented to the- meeting of the Hntbor Board yesterday. Tin- report as follows: "Very c.-iloi'iil investigations have been carried out over a considerable area of country with the yiew of ascertaining whether a suitable stone is available in the quantities required for breakwater eons.t motion. Over twenty different sites have been visited and all .known outcrops inspected in the endeavor to locate the most suitable for our requirements. The stone formations nearest to Gisborne —the. Ormond series—were inspected first, six .separate sites being visited, viz., Waihirere, Gray's Hill, Heston, AloLaurin’s property, Benson's _ property, Patutahi quarry, Gentle Annie quarry. The evidence disclosed at the above-mentioned localities was or a lar from satisfactory nature from the point of view of our needs, indicating a very considerable proportion of overburden, most of tiny rock being too soft to stand blasting. Tim Bukauroa district was next visited, stone in six localities being inspected, viz., Tomblcson property, Ranger's property, AJc-AHan’s properly, AlcLoughiin's property, Shaw’s property, Clark’s property. The stone in this district is sandstone of varying degrees of hardness. 'lonibleson’s probably would not yield very .large stones, the strata being comparatively thin, not more than 4ft in thickness. .Shaw’s gave much better indications, the exposed sandstone ! being of considerable height and, the boulders large. The indications on i the remaining properties were not so ; favorable, there being more overbtir- j den and the .quantities of rock instil- j Helen t . |

"The Alatawni district was also intrestigated, inspections being made at Hie following places:— C. Richardson’s property, S. N. Richardson’s property, Smith’s property, Gray’s property, Blair’s property. _C. Richardson’s property on Trig. K. was very inaccessible, and the stone (d solt quality. The stone on C. \Y, Richardson’s property was only a small outcrop and without evidences indicating any great quantity. Smith’s property adjoining the waterfall gave evidence of considerable quantity of good stone of varying grades of hardness. The rock on Grnv s w fis of shattered nature.*, and it is doubtful whether large stone could be obtained. The distance from the railway is considerable. Blair’s property gave evidence of big stone at the lower levels and thin strata above, but tho total quantity is short of our requirements. “Inspections were made of Green’s property, Otoko, Sherriff’s at Waiko11n, but the distances from the railway were too great to warrant further consideration. The stone at Hick’s Bay was inspected also, and although an ample quantity of good stone was found, tho conditions in the Bay and the. sea journey to Gisborne preclude operations at t his site unless we fail to obtain suitable stone nearer to hand. “After reviewing Hie loregoing localities it was considered that, the following sites gave tho best indications of proving satisfactory: —-Tombleson’s (Rakanvea), Shaw's (Rnkanroa), Smith’s (Alntawai), Blair's (Matawn i.h Ear flier investigations were undertaken on oaeii and shafts were driven at different levels over the respective areas to ascertain tile amount of overburden and the nature of the ruck at diifeiont levels. Those mves- j Ligations showed that the overburden : on Tombleson’s property is negligible, ] but the strata is thin, with, clay beds between, it is probable that though a fair quantity of medium-sized stone j could lie obtained, it was considered ; unlikely to yield really big stone m large quantities. 'Further, the proper- . tion of material to lie handled that would not be suitable for breakwater purposes would be in the vicinity of j 33 1-3 per cent. The railway to con- , nect the quarry with the main line would bo about a inilo in length, fluti the construction of tho junction and necessary sidings would not be an easy proposition. The site on Blair s property which adjoins the main line about one mile beyond Mntnwa.i was opened up some ten or twelve years ago bv the District Engineer of the public Works Department in connec- i tion with the construction of the line. The material at tins site gives indications of good big stone at the lower levels, but above! this the strata, is of vowins: tlrieknetfs not exceeding 411. ■ witii day beds between. die overburden is fairly heavy, and with the mullock intermingled with the good stone would amount probably to over 40 per rent. The chief feature or . this site is its accessibility and being . on tlie main line would cost very little to eoTinoct up. Further inspection of Smith’s nroperty revealed indications of a large quantity, in a high face, ot : good, solid stone. Several shafts driven into this showed the stone to ho of varying quality but of considerable mass formation. Blasting operations were necessary to get some distance into the solid, and though thcic are sections of only fair quality, there appears every likelihood that it will be. nosdble to obtain a large quantity of -‘mod stone and in ornctiOallv any . size” desired. The distance or the kite from the main line is about one mile and no difficulties are anticipated in making the .necessary connection to an assembly yard adjoining the nuarrv, but it'would be necessary to instal a steep incline between tho ounrrv face and the assembly ward over which haulage would ho clroetctt bv a. winch 01 friction' drum. . ' “The main disadvantage of this site u that the quality of the stone varies so much over a comparatively small area that the proportion of. unsuitable material to be handed, could not be closely estimated—a pny nortion of 33 1-3 per cent is assumed. Shaw’s property on further inspection gave evidence of very little overourden the indications being that the stone is of an homogeneous nature , throughout and exists m considerable mass from which large stones could bo obtained. It is probable, that not more than 2b per cent, of unsuitable lector ini would have to bo n find led. The situation lends itself to easy operations. the faces beiiur high and vertical and of considerable lengths, with easy rail access. The distance from the main line is about 3 miles, but no difficulties in linking up aye- expected I therefore recommend the site referred to as being situate on Shaw's property as being the best site on '.vb’-’h to develop quarry operations. The chairman. Mr G. Smith, said that the' report indicated that the Engineer bad investigated the posttion verv fully, and lie moved the adontion of the report. Mv Walk's asked if the Eng.peer had gone into the question of frettinjy shingle from Napier and making hollow ; blocks. 'l'lin chairman said the question was , a little, out of order at this stage. j The Engineer, in reply to Mr. Corson, said that there was plenty or stone on Shaw’s property to build the harbor. . . , The Engineer mid. in reply to -Vr ; Shcrratt. 'that Mot.uhora stone was • not suitable as it would not eua.rrs in large blocks. ~ The chairman said in reply to Jlr Tomblcson that there was no reason whv they shoo'd rot sell some ct the stone to local bodies when t.icc had onc’erl m their (marry. ■\ r ' f.'ie uic—V.rs 't/ 1 ius- c" "d samples cf t'-e stone', the Engineer's . re’iort was adopted Referc'ce was made lv- the chairman to the proposed tri--> of members to the site of the ourrrv. anil In- - stated that thev should make the inspection for the rurpn-e of seeing : the amount of work which the Engineer had put in. Ho suggested that

instead of fixing a date, it should be left in his hands to communicate with members when the weather was suitable. ! I Ins suggestion was adopted. | It was decided, on the motion oi > Hr W. G. Shcrratt. that steps should be taken to acquire the quarry site on : cjUniw’s nroperty, either by nyI preaching him privately or b.v takn.g 1 it under the Public Murks Act.