ESTIMATES UPSET

Taranaki Daily News, 5 March 1935, Page 6

ESTIMATES UPSET

AFTERMATH OF FLOODS

MANGAOTUKU DIVERSION

MONEY HELD MEANWHILE

REPORT BY THE ENGINEER

The estimates of expenditure for 19351936 on New Plymouth borough works has been completely upset by extensive damage to hydro-electric works and waterworks caused by the recent floods, and the possibility that the borough council will have to budget for the deviation of the Mangaotuku stream. A special meeting of the council will be held on Wednesday week to consider the position and, in the meantime, neither the transfer of £12,000 to the new library fund nor of £lO,OOO to the electricity reserve account will be made. At last night’s meeting councillors admitted that the council’s Immediate fin-* ancial position had been completely altered by the flood damage, and they decided to hold over all matters of granting increased subsidies to various park societies until the exact position is determined. The possibility and cost of diverting the Mangaotuku stream to prevent a recurrence of town damage was the subject of a special report by the" engineer, Mr. C. Clarke, who explained, that his report was merely a preliminary one and did not take into consideration the diversion or treatment of the Te Henui. A rough estimate of the cost of diverting the Mangaotuku at Calvert Road, was shown as £9250. The plan suggested provides for a concrete tunnel” to carry flood waters overflow in the first instance, but large enough to carry the entire stream ultimately. Temporary work to remove the most serious blocks in the streams will probably be undertaken at an early date. During a period of approximately 12 hours when the flood was at its highest, he estimated the average flow of the Mangaotuku stream was approximately 550 cusecs, stated Mr. Clarke. A serious wash-out on the Omata Road probably increased this flow by about 50 cusecs at the height of the flood period. STREAM BADLY CHOKED. The stream, unlike most streams adjacent to New Plymouth, was sluggish, and was in many places badly choked with willow growth. Had this not been the case the flood experienced would have lasted for a shorter period but would have done considerably more damage during its height. From where it crossed the borough boundary to Dawson Street the fall in the stream bed would average approximately one in 260, from Dawson Street to Queen Street approximately one in 90, and from Queen Street to the Huatoki River approximately one in 120. From this it could be seen that whatever was done to clear or divert the stream below Dawson Street would not relieve the upper portion from the possibility of future floods. Again, the fall available between Queen Street and the Huatoki showed conclusively that flood waters could be taken by the stream without serious flooding, provided adequate precautionary measures were, taken to keep the stream bed unobstructed and clear of silt and debris. ‘No doubt public opinion would require the,.council to consider the diversion of the Mangaotuku stream, and for this reason he had prepared estimates for the diversion at the point where the stream crossed the Calvert Road, and at Queen Street in front of the Taranaki Club. The estimates were based upon a concrete-lined tunnel in each case which, although deep . and large enough ultimately to take the whole stream, would in the meantime function only as a flood overflow. . Diversion at Calvert Road would cost £9250; diversion at Queen Street would cost £4500. These estimates were in the meantime only approximate, and were subject to revision upon the completion of detailed drawings. .. . - • In considering the diversion of the stream there were many features that should be carefully considered. The more important of them were:— (1) Future flooding of the central business area: This could be overcome without diversion of the stream, by cleaning up the stream bed, and by the removal of many of the existing obstacles to the free passage of the stream. ? N

C2) Flooding of that area adjacent to the stream above Dawson Street: This was the most difficult to overcome, and was the strongest reason for diversion, Much improvement could, however, be effected by the thorough cleaning qf the stream bed, together With some straightening between Calvert Road and Dawson Street. •

(3) The probable future saving in building costs where buildings abut ot cover the stream:.No doubt the diversion of the stream would save maiif thousands of pounds in the cost Cibuilding in the central area of the town in years to come.