WAIRARAPA EAST COUNTY.

Wairarapa Daily Times, Volume 6, Issue 1800, 29 September 1884, Page 2

WAIRARAPA EAST COUNTY.

Tee following report was read at the meeting of the Council 011 Saturday :~ Sir,—l have the honor to submit for your consideration the following short report on the Waingawa and Waipoua bridges. Waingawa Bridee.—Tho accompanying plan and section show the condition and levels of the river bed at the bridge in September, 1881, and also on the 25th September. 1884, On the section tho black line indicates the surface of the ground at tho piers of the bridge in 'Bl, and' the red jno indicates the surface of the ground affllfo same piers in 'B4, You, will see thapno C material addition has been made to tha * deposit of flhingle'at the site of tho bridge durug the last three years, and at several points under the bridge acid especially at the Carterton end thereof, a considerable quantity of material has beon scoured out.

There is now quite as much room for flood waters under the bridge as there "was three years ago, but for some time previous to September 1881 the Rilling up of the river bed under tho bridge was very great, I would recommend that 75 feet be &dded to the Carterton end of tho Bridge,' aud 100 feet to the Masterton end, these additions to be made in short spans which will encourage a deposition of shingle, etc., about the end piers, I would also recommend that that part of the left bank, between the railway and road bridges, be made good where it has been damaged by the recent flood. This could he effected either by embankments or fascine work. I am of opinion that the overflow at the Masterton end of the bridge could be diverted at a moderate cost, from its present channel, and made to flow under the bridge. In that case the ted would be somowhat contracted but -would be sufficiently wide, except in times of very high flood. The contraction of I he bed would tend to lessen the deposit of shingle durina floods about the centre piers. If this plan bo adopted, the cost would be considerably less thau if tho bridge was lengthened at the Masterton end as well as at the Carterton ond. Appended is an estimate of the cost of lengthening As bridge at. both ends and making goodwfl approaches, and a separate estimate of the cost of diverting that part of the stream now flowing acruss tho road at the Masterton end of tho bridge, making good the left bank where it has been damaged by tho overflow, and restoring the approach to the bridge, Waipoua Bridge,—lmmediately after the erection of the old Waipoua bridge, the bed of tha river near the bridge began to silt up, and has continued to do so ever since, notwithstanding the large amount of material that has been taken from it -from time to time, The overflow over which the new bridge was erected, commenced to give trouble very soon after the old bridge was finished and tho Provincial Government .spent a considerable amount of money in making good the breach from time to time. Every successive flood contributed to the Billing up of the old bei and increased the amouut of overflow. Tca

remedy the existing evil, there were two. courses open, either to make a strong and expensive embankment to confine the river within reasonable bounds (the embankment t would be necessary because much of the ad- 'r jacent land was nearly on a level with tha rivoi- bed, causing the silting up of the bed to progress very rapidly, in fact allowing the flood waters to spread out over ,tbe adjacent lands would be equivalents* enlarging the section without increasing® slope, the velocity must therefore be diminished and floating matters must be deposited), or build a bridge ova: tbe.uew channel, which was the plan adopted. After the erection of the new bridge the silting up of the old channol was effected more rapidly than was at first anticipated. So rapidly . indeed did this take place that for a long time previous to the recent flood (except during high floods) all the waters of the Waipoua flowed down the new ohannel. It

iL- 'nas diffioalt to foresee tbat this would take IBfplace eo siou, and mote difficult still to ■ desigu ft structure that would exaotly fit a ouamwl several years previous to it's being formed. The changes mado by the recent flood render the extension of the new bridge ii necessity. I would therefore' recommend that a new span similar to the existing one be added. Appended is an estimate of the >■ cost of the proposed works. I havo, etc., John Kino, County Engineer.