THE PAREORA RIVER CONSERVATION WORKS.

Temuka Leader, Issue 2737, 13 November 1894, Page 2

THE PAREORA RIVER CONSERVATION WORKS.

The protective works just completed at the Pareora river bridge will doubtless attract the attention not only of the settlers primarily interested, but also of ratepayers generally who reckon what a costly item the maintenance of bridges and fords over onr erratic streams has proved in the past and may prove in the future. Those of our readers who are acquainted with the main road south of Timaru will recollect that the Pareora riverbed is a wide oue. It was originally spanned by one costly bridge, but successive floods scoured away the approaches, and two supplementary bridges bad to be erected—oue at the norrh, the other at the south, with embankments between. These bridges have been in disuse for some years, aud there has been for some time a certain agitation for their proper repair or reinstatement. As a compromise, and it is hoped as a .preliminary to the erection of a new bridge, the present protective works have been erectedjfrom the plans of Messrs Meason & Marchaut, and under the immediate supervision of Mr Merchant, who has devoted much thought and experience to this particular class of work. The main idea of the work is to train the river into a defined channel, thereby not only protecting the banks, but minimising as far as possible the space to be bridged. For this purpose two trenches—one on the north sud the other on the south, each nine feet wide in the bottom—have been scooped out, and with the material excavated banks have been formed from the ends of the centra bridge up stream on the north side almost at right angles to the bridge, and upon the south at an angle of about 65 degrees to suitable points on the river banks. The south embankment is 23 J chains and the north 21 chains in length, with a width of 5 feel on top, with slopes graded 1} to 1, aud an average height of about 6 feet. The banks contain, ronghly speaking, about 9000 cubic yards. Along the trenches at the foot of the embankments a substantial fence has been erected in the following manner. At every 21 feet iron piles 12 feet long have bean driven to a depth of 6 feet. Substantial strain-. iug posts, bolted to iron piles 17 feet long, have been erected at the ends of the fence. At every 3 feet willow stakes 12 feet long, with diameters of 4 inches at the smallest end, have been sank to a depth of 2 feet, and these are strutted or stayed with other stakes of similar size, the two being firmly lashed with font turns of No. 8 steel wire. Upon this substantial line of stakes 19 wires have been strained aud stapled, the lower 10 are No. 4 galvanised steel wire, the remainder No. 6 black wire. At the back, between the fence and the embankment, what are technically known as gorse stops have beau put, some 30 in all. These are constructed of 12 heavy willows set in quadraugular fashion, and filled op with gorse faggots securely bound together, and also at the back of the fences some five or six hundred willow stakes five feet long have been planted. The river fences aud embankment are enclosed with about 50 chains of standard, post, and wire fence of substantial construction. At the present time the whole of these willows have grown, and their branches will soon interlace. Their fibrous rootlets are seeking hold in every direction, aud by no great stretch, of imagination oue sees in a year or two a perfect wall of vegetation. It must be mentioned that the trench is oarefolly graded, so that the ordinary flow of water is very gentle, and it will be understood that the effect of the gorse stops will be to cause dead water and prevent scour along the bank. As a further precaution willow trees are to be attached to the fence, and allowed to float in the trench. Similar fences on a small scale have proved very successful in connection with the head races of our water-supply works at the Teugawai river and elsewhere, and there can be but little doubt that under ordinary average conditions the Pareora works will prove equally efficient, and in fact practically solve the question of river control. At Pareora, as a supplementary work, the main bridge has been partially repaired, and the decking covered with shingle. In this condition it is available for sheep traffic. The contractors for the whole of the work are Messrs Gregan aud Mulvahill, «ho have carried out the engineer’s plans most efficiently, and Mr James Radford has acted in the capacity of clerk of works, a position his varied experience upon similar contracts has eminently fitted him for.