BOROUGH WATER SUPPLY

Hokitika Guardian, 18 October 1927, Page 1

BOROUGH WATER SUPPLY

itKPORT BY MR J. «. LANGFORD. At the last meeting of the Hokitika Borough Council held on Friday evening the following report was received from Mr J. S. Langford:— Following receipt of instructions . have compiled the following particulars in connection with the consideration being given to the matter of future arrangements for the above undertak-

ing. I understand the issue is covered under (ho following heads, — (1) Assurance of continuation of adequate supply with associated cost of maintaining the existing pipe lines. (2) Cost of providing new pipe line from source to reservoir or some alternative method of obtaining reliable supply. (3) Purity or otherwise of water being supplied and possibility of obtaining supply elsewhere. The chief points for consideration are quantity required and purity. In the matter of quantity the original scheme was designed for a supply of (i.) gallons jrm* head per head for a population of three thousand and f understand that when the last test was made the flow into reservoir was 130 gallons per minute or approximately equal to the quantity for which the scheme was designed. This supply evidently just satisfies the demand and this fact, in view of the smaller population served than that which was allowed for. may he attributed to two

(a) Leaks in the reticulation. (h) Greater dcnifmd per head than was the general practice years ago on account of dovel opulent in living conditions, improved sanitation arrangements and the requirements of the Public Health Department regarding the thorough cleansing of apparatus used in industries dealing with goods lor human consumption Regarding purity of supply: The pTecent source. Lake Kanieri. having a watershed protected as a Scenic Reserve, offers an excellent source. With the intake well below the surface as it is and a surface overflow close at hand for removal of flotsam, contamination should he a minimum, hut it would seem that a large proportion of the water being delivered into the reservoir is not entering the borough pipe line at the Lake intake, hut at the auxiliary intake at Kanieri Forks Power Station. This is indicated by the difference in How as measured into the reservoir before and alter the connection wa’s made at Kanieri Forks. The passage of this water through seven miles of open race through country, unprotected as a Scenic Reserve is, would lie regarded as unsatisfactory in general water supply practice and 1 believe is open to condemnation on account of the possibility of pollution. T'he interesting discussions which are taking place in Wellington at the present time regarding extension of water supply for that city are worth noting on one point al least in that they include tne opinions of highlyqualified persons. The definite exclusion of the Pukratahi River and its watershed from tlie Mutt River sVheme merely because the railway line runs parallel to the river for some miles, without any settlement, indicates the importance attached to possibilities of pollution. Giving consideration to the reliability of the present scheme 1 have lieen able only to obtain verbal reports of the work done in maintaining the present line, hut the ease with which it is put out of action h.v intermittent rise in pressure indicates that the pipes or tlieir fittings are deteriorating rapidly and have probably approached a point where they should he renewed.

You have probably had close estimates of the cost of renewal and for the present consideration 1 approximate this cost at £20,000 from reservoir to Kanieri Forks and £35.000 from reservoir to hake Kanieri with a pipe of sufficient dimensions to give satisfactory supply for the future. The annual interest on this outlay would lie £l,lOO and £1.025 per annum respectively which, with sinking fund added, makes the total capital charges £I,OOO and £2,025 per annum for tlie

respective a!ternati vcs. As tin alternative supply consideration might reasonably he given to tlie possibility of a deep well source and the satisfactory results of several bores sunk in the gravel beds adjacent to. and in the Borough, indicate j that a satisfactory supply is almost certain from that source.

If such should prove to he the ease advantage could he taken ol the increasingly popular practice of utilizing the electric power supply to provide the necessary pressure from a deep well source and as a means of avoiding the heavy capital cost usually involved in gravitation schemes, ns in the case with your installation. The Hokitika Borough installation lends itself to such an alteration without heavy expenditure in that the reservoir and reticulation are connected hy an Bin. pipe which could he tapped at a point adjacent to where a well might he expected to give satisfactory results at the Borough Boundary East, and there connected to an automatic pumping station which would pump directly into the reticulation, using the reservoir in the nature of a tower to accumulate any excess over immediate requirements and to. stabilise the pressure. An advantage of such a scheme would lie the elimination of much of the pressure loss when largo draw-off is required for fire purposes as tlie pumping plant could he arranged in such a way that it would give extra discharge at such times thereby doing away with the friction due to approximately one mile of Sin. pipe, which is really the cause of pressure drop. A 15-li.p. pumping plant of modern design would supply the quantity now being procured from Kanieri namely 130 gallons per minute and if a plant of 22 h.p. were installed approximately 200 gallons per minute could he delivered and this power would enable your Council to obtain the wholesale minimum rate prescribed by regulations. being £l2 per h.p. per annum, which, with the conversion charges added, would amount to £275 per annum.

Such a plant installed complete, provided the water level in well were not more than 40 feet from the surface would cost approximately £SOO complete with building and connection to existing main. To this would have to he added the cost of drilling the well and casing, same which might be estimated at £IOO, making Hie total capital cost £OOO. Tlie annual eliargen thus involved would he £6O per annum (no attendance being required) making the total supply charge £335 per annum.

A further advantage of this scheme

is its adaptability for extension at small cost and in view of the almost certain necessity for providing a sewerage system in the future tins feature warrants due consideration. Should you desire any further information in connection with this matter I will be glad to assist.