CORRESPONDENCE.

Hauraki Plains Gazette, Volume XXXVII, Issue 5020, 30 August 1926, Page 1

CORRESPONDENCE.

USE OF PUMPS IN DRAINING.

CTo the Editor.}

Sir—l have noted with interest the rapid spread of the l movement among Plains farmers to compensate for the deficient fall of most of the Plains drains, by means of pumping. I have long foreseen that the drainage problem of a large area of the, Plains will only be satisfactorily solved in this way, and possibly some points in that connection that have occurred to me may be of interest.

In the first place, any single farmer, or small group of farmers, who. may desire, to instal a pump at their outlet, must cither dam themselves off from their neighbours who are outside the scheme, or relieve the latter’s drains fre,e of charge. Provided that only their own private drains cc.uire: to be dammed, as would often be the case in a one-man installation, this would present ho difficulty beyond the wastefulness of using a multitude of small pumping plants. But, in the. case of a group of farms all discharging into one or more Government or public drains, the damming of these, and of connecting cross drains, at the limits of the area to be pumped, would in cases be impracticable, unless all the. farms discharging into those drains are contributaries to the pumping project. In short, any area to be pumped must be selfcontanied and not connected by any public drains with any other area. Where a drainage board exists, the board would of course ins.tal the pump, and see- to it that they allowed no outside water into their area. But a small group of private farmers is in a different position, because, few small groups of farms are entirely cut off—aS regards drainage—from all neighbouring groups, and when it became necessary to drain a connecting drain, the man on the other side of the dam would, in nine cases out of ten, strongly object. For these reasons, and in the interests of economy, it seems to me that areas' .dealt with should be as large as conveniently possible, and preferably that several such areas should be grouped, unjler one drainage board or equivalent authority. x Several small groups have recently decided to instal pumps, and many more, no doubt, will follow. Would it not be wise, before going any further, to ascertain whether it wciild not be more economical to deal with the matter on a larger scale ? Another point to bear in mind is that though the pumps will only be required to work during a small portion of the year, yet during a long spell of wet weather in the winter it is highly desirable that they should be capable of handling all the wa,ter that falls. This desideratum is probably out of reach, but I think that at least lin per 24 hours should be allowed for. On this basis, allowing for a reasonable lift, a-motor of 30k.w. should suffice for about 1000 acres. The point should be carefully inquired into, whether or not the saving of interest and sinking fund on first cost by installing, say, half this capacity, would be outweighed by the damage to pastures consequent on the pumps taking twice as long to clear an abnormal fall of rain.

Finally, it is. absolutely essential td make sure that the main drains leading to the outfall are adequate to s.upply the. full capacity of the pumps. This is a point requiriing very careiul consideration, fdr it is useless to instal a pump capable of handling lin of rainfall in 24 hours (which is abort equivalent toi 1500 gallons per minute for every 100 acres) if the size and gradient of the drains are/ins.ufficient to keep the pump supplied. L. SHELFORD BIDWELL.