Ngaruroro River Control

Hawke's Bay Tribune, Volume XXVI, Issue 80, 16 March 1936, Page 8

Ngaruroro River Control

(To the Editor.)

Sir, Ratepayers in the Rivers Board district are uemg asked to support a. scheme for the control of the Agaruroro river and to that end are asked to vote tor a loan ot £66,G00 which with £120,0G0 being supplied by the Government will be required for the work. 'lhe board's chairman, Mr Lassen, and the engineer, Mr Rochfort, ere sponsoring the scheme beiore ratepayers. It is claimed that the scheme is approved by the Public Works Department’s engineers. It may be approved by the t'ubjie Works engineers but is certainly not rccommenaid by them. They recommended the “E’ 1 scheme, if no better case can be stated tor the Rivers Board scheme than was presented at Pakowhai, it js a very weak one Briefly put the scheme provides ior leaving the river channel where it is but improving it and allowing the greater part of the waters to oi erflow where they do at present but enclosing them between high banks. The bank would join up with the Tutaekuri bank so that Pakowhai will be two banked rivers with no getaway for the flood waters should either river break its banks above Pakowhai. it is not proposed to bridge the overflow at Pakowhai but the possible necessity for this in the future is recognised though no protection is made for the cost, estimated at £20,000. Whenever there, is sufficient flood to rise in the overflow access between Hastings and the north via Pakowhai will be blocked. It is anticipated this will occur four or five days a year. That is provided the overflow channel does not scour in which event access might be blocked for a considerable period. It must be also borne in mind that only 80 per cent, of the highest estimated flood is provided for. A 100 per cent, flood may do infinitely more damage because of 80 per cent, protection than with no protection at all. At the Pakowhai meeting the Tutaekuri scheme was explained and it was shown that the channel had improved because of the control works. This of course was natural and no authority ever doubted that anything else would happen. This was held up by inference as what would happen with the Ngaruroro scheme, but the position is vastly diflierent.

The Ngaruroro channel below Pakowhai is depreciating because of its flat grade. Even though it be improved it will continue to depreciate until * gradient is established at which the river will carry its shingle to the sea. Before that point is attained the river will break away elsewhere. This statement is not arguable.

Under the scheme a temporary improvement mar take place but sooner or later the river will go down the overflow or break away elsewhere, or do both. It may be on the Pakowhai side or it may be on the Twyford-Clive side but with this aspect I will deal again. In answer to questions at Pakowhai Mr Rochfort, with sublime naivette, did not anticipate sufficient scour in the overflow to interfere with road traffic. He did anticipate sufficient scour in the Tutaekuri-Waimate, where it crosses the bed of the overflow, to keep that stream clear of the silt, etc., which will find its way there during Hooding. Where did Mr Rochfort get his experience of scour in channels that ho can use its useful action or eliminate it at will? Was it in the Tutaekuri channel by Westshore Embankment that silted up the Inner Harbour ?

According to Mr Lassen the Rivera Board has spent £BOOO on engineering advice but to what effect? This advice culminated in the most comprehensive engineering study of the position and the committee of engineers presided over by Mr Baker, A.M.1.C.E., of the Public Works Department recommended the “E" scheme at a cost of £240,000 to deal with both rivers.

Mr Lassen told us that he opposed the “E” scheme “because he knew it would never be agreed to." What logic! At the time, the expense of thia scheme was raised as an objection, but now Mr Lassen is sponsoring a scheme to cost infinitely more. Here let me say that all the engineering advice of any value has recognised or recommended the superiority of some diversion of the Ngaruroro from above Pakowhai to join with the Tutaekuri. Mr Lassen told us at Pakowhai that the Tutaekuri scheme was costing over £lOO,OOO and the proposed Ngaruroro scheme is to cost £lBO,OOO plus £20.000 for an overflow bridge which may be necessary. That is a total of over £300,000 for a scheme which is certain not to be a permanent solution of the flood menace.

Will Mr Lassen attempt to justify his action in this matter? Will he or will the board's engineer give one Instance of a similar method of dealing successfully with river control?

The “E” scheme was a permanent solution and provided ior 100 per cent, floods in a channel that would improve itself as the Tutaekuri is doing. The estimated cost was £240,000, that is over £60,000 less than the present scheme is to cost

Ratepayers will do well to turn down a scheme which has nothing to commend it from an engineering point of view, which is a waste of public money, which will jeopardise lives and property particularly at Pakowhai, and which will definitely not control the Ngaruroro river.

Will Mr Lassen also explain how the Rivers Board rating is controlled by the Hawke’s Bay ratepayers as a whole when he knows that there is a bigger proportion of ratepayers in the Rivers Board district in favour of unimproved rating than there is in the county as a whole. —Yours, etc., T. MUIRHEAD CRAWFORD. Pakowhai, March 6, 1936.