WATER REQUIREMENTS FOR 1959

Chronicle (Levin), 17 September 1949, Page 4

WATER REQUIREMENTS FOR 1959

Maximum 1,250,000 Gallons A Day, Expert Contends

Basing his calcula^ions on 50.00 of population, Mr. H. F. Toogood, MJ.C.E., of Wellington, ha$ assessed Levin's domestic and industrial water requirements by 1959 at not exceeding a maximum of 1,250,000 gallons a day. No calculations, he said, ,could take into accountthe free use of garden hoses and leaking taps ; only firm administration \could check these items. For any large increase, however, added Mr. Toogood, it would appear that industrial activity would be a major factor and it would rest- with' the Levin Borough Council to evaluate this possibility. ilis population estimate had been based on the fact that increases of the past 10 years had averaged 100 a year and, assumnig that • rate of increase was maintained, Levin's population- by 1959 would be 5000.

These comments were contained in a preliminary report on a possible scheme of water supply improvement, the object being to review the existing waterworks in respect of capacity to bring into focus the aetual immediate problem and to ©onsider fhe fuvUre requirements. The appointment of] Mr. Toogood, a waterworks en- 1 gineer, for the task was authorised at the annual * meeting .of the council, for which a sum of £100 was allowed in the estimates. Topulation Growth. In 1939, when the previous re* pprt was prepared, the borough population was 2750, reported Mr, Toogood. t Tn ad'dition the rural services were 232. Today the respective figures were 3780 and 306. In 1939 it was calculated that the demand could he met by a suppiy of 500,000 gallons a day, this amount supplying 100 gallons psr day per head to the borough, 27,000 g.p.d. to the State and 850

g.p.d. to tne rural connections. in addition 125,000 g.p.d. was added to meet contingencies which might arise. Applied to the - present. population, these figures-. would indicate that the present demand should be 790,000 g.p.d. If this was so and the iftfiow to the 500,000 galloh reservoir was maintained at 900 g.p.m., there would be no occasion when the reservoir would be empty. The waterworks, overseer, -Mr. Greig, had stated,*' however, that th© reservoir had been emptied and this being so investigation would have to be made as to the cause. Three obvious reasons were that the demand exceeaed 790,000 gallons per day b.y nearly 40 per cent.; the infiow into the .reservoir was less than 900 g.p.m*

excessive leakage from domestic, rural and other taps and connections was taking place. Referring to future requirements, Mr. Toogood said that the growth of the borough had been consistent up to the present, but with land in the district, served by Levin, now closely sett ed, the' future growth must depend on other • factors. Many 'people had retired to live in Levin. A sanatorium would be erected in the near future, which, besides *making a direct demand for water, woui'd cause some extension in the population. ft was also proposed to -extend the service to Waitarere, thus adding some 20 rural services $ind ,130 'sea,-side houses. ExtenSions to Ohau and Hokio were also contemplated which, if made, would add to the demand. The additiona! rural and household consumers, with the rural extensions contemplated, might -be 450. When sewerage was installed, the exlra demand might reach 15 gallons per head per day and this would require 75,000 g.p.d. The sanatorium couid be expected to require 40,000 g.p.d, A contingency allowahce, in addition to the amount previously allowed, should be taken into consideration to meet possible industrial development and this might be 150,000 g.p.d. "The grand. total on the above . assumptions is that when the borough population reaohes 5,000, and if reasonably firm administration is carried out, the maximmn demand should not exceed 1,250,000 gallons per day," Mr. Toogood added. Adequacy of Present Source. "The headwaters are fed from the Ohau-iti stream with. a watershed of 13 square miles. This area could be relied upon under the most adverse conditions to yield 2,000,000 gallons per day. There are objections to this source of suppiy due to discolouration of water in times of fresh. On ordinary occasions the water is of good quality. In 1940 it was proposed to provide a more suitable intake which would keep the tunnel clear. Uhfortunately, this work was stopped by a previous council after the tunnel was cleaned and rock removed in anticipation." The tunnel, when clean, was of ample capacity, continued Mr. Toogood. It must, therefore, be supplied with an adequate silt trap. Arising out of a daily demand of 1;250,000 gallons, the hourly demand was likely to be 100,000 gallons .Ahd the average demand 1,700 gallons a,minute. • After going into the difficulties ih a more detailed form for the benefit of the council, the engineer went on to make the following suggestions:-— In regard to water discolouration, he stated that filtering would be costly in relation to the requirements. Storage would have to be of cpnsiderable dimensions to provide settlemenfc ahd could only be effective by holding suffh cient water to enable the suppiy to the storage to be cut off while the fresh lasted. An alternative suppiy would include pumping from a suitable well if such were available, - and this promised to be an immediate solution. A, pump capable of deliveiing 1000 gallons . .per mlnute - . would -more :

than meet present requirements, and he recommended that it would be wise to adopt this size of pump. The water could be delivered into the '500, 000 gallon reservoir. A pump such as indicated could be ; supplied and fixed for next summer's demand, where as extra storage or any other « source of suppiy could not, 2x& avlded It. had been suggested that an •artesian suppiy might be obtained ih the vicinity of the borough. When a suppiy from an undergrouhd source was being considered the service of a geologist would be warranted, said Mr. Toogood. A polnt that might have been overlooked by the proposer, however, was the • fact that the added suppiy .would have* to be* forced into the reticulation. * with a sjatic head of about 250 feet, -as against 80 feet if a suitab.e well could be found near the reservoir. Taking into consideration frictional resistance, it was possible that three to four times the pqwer .would be required to deliver the same volume of water. A bore would not suppiy the extra water now belieyed necessary and a well or a number of them would be required. * Final Summary. In his summing up, Mr, Toogood reported that if the present waterworks, including the intake, I were maintained in an efflcient state and if leakage from taps, I etc., could be avoided it was believed that the system would .suppiy the present demand except under two speciai circumstances — an excessive draw-off in summer, prqsumed to be for hosing, and the necessity to exclude discolour-

ed water when floods occurrea. Both these circumstances were intermittent and could be met by ancillary suppiy from pumping. Whether or not pumping was the most economical means of obtaining an extraordinary suppiy might be queslioned at the ed with assurance. If immediate moment and cou'd not be answerrelief- was to be obtained, ; it seemed the only resource available. _ It would certainly be a method which would involve the loweso capital c6st. ' Extra: storage was desirable, but with materials and labqut ih short supp y it could not at present be entertained. In conclusion, he advised that the economie yalue of rural water suppiy should again be examined In view of the large proportion of water required for these services and the liability of misuse on flat rate charges. The above report was presented to the council at its last meeting and was referred to the works committee for discussion and report, and its opinion will probably be presented to the -council when it meets on Monday night. The engineer is stlll carrying out investigations.