BOROUGH DRAINAGE SCHEME

Pukekohe & Waiuku Times, Volume 2, Issue 139, 24 October 1913, Page 2

BOROUGH DRAINAGE SCHEME

SUBMITTED BY THE ENGINEER ESTIMATED COST OF £BSOO COUNCIL DEFERS CONSIDERATION

At its meeting on Wednesday night the Borough Council received the report from Mr Lockie Gannon, C.E,, on the proposed drainage scheme for Pukekche. As the business paper of the evening had been a heavy one it wes decided not to go ir.ti the question thai night. The report was as follows: DRAINAGE AREA. The nature of the soil is very retentive, water and sewage consequently Co not percolate at all fieely; the result is that many parts of the borough have become permeated with organic matter. Tha danger arising from insanitation due to slops, bath, sink and w.c. water remaining in the suil is a danger which with the continuous growth of the borough must ever iicrsase. "That part of your borough that it is proposed to drain ha? an area of 283 acres, defined as follows: From Buckland's horse bazaar to Jackson's earner; thence to Victoria street, a'eddon street and Cape crossing; and thence along railway line to entrance of goods whsd. The drainage to be 2J chains outside this line with the exception of that part which runs along the railway line. The probability is that the greater portion of this area will continue to be residential and allowing 4 to 5 houses at an average of 6 people per house, or an average of 27 people to the acre, there would be a population for the whole area of say 7500; this estimate would be probably extreme, the rresent population is approximately 400. REQUIREMENTS OF A DRAINAGE SYSTEM.

"Flushing manholes at the heads of drains for the purpose of keeping sewers cleansed to be supplied with water from Mie nearest hydrant, and discharged by lifting a trap or shutter. "It is imperative that all sewers, drains, and connections shall be absolutely watertight, and this can only be effected by beddirg the pipes in concrete and making cement joints; otherwise the soil will become foul. "As noted it ia most important that a suitable place should be provided for discharge of sewage. This undoubtedly lies at the low-lying swamp land close to the crsek at the northern end of the borougn. This outfall is les3 liable to pollution, and the water frcm the creek, which Ir.s been kept under close observation by me for same considerable time, sweeps in a strong continuous How. This stream ia fei by Hickey's stream or dam, which i 3 active both summer and winter, and which wouid materially assist in keeping tha creek well sluiced. The danger of contamination due to septic tank effluent will thus be reduced to a minimum. The Council will have to acquire a few acres in this vicinity for treatment v;orks. Care has been taken to keep the treatment works well above flood level.

"The sewsge to be treated will be a domestic one, consisting of bath, sink, s!op and w.c. water. This system is known as the 'separate' system. The sewage will ba put through a complete bact-rio-lozical method of treatment, and it will be necessary to install a mtdern purification plan*, to thoroughly treat the sewage. This system requires very little attention. FURTHER CONSIDERATIONS.

"The following matters must be considered in propounding a drainage scheme for an inland borough Euch 9s Pukekohe, and have had due consideration in übtaining the data for the preparation of this report. The scheme where possible should be a gravitational one. This avoids the necessity of pumping, reduces the expense of installing pumping machinery, and effects a considerable saving in working and up-keep, ar,d leads to more satisfactory results. "There should be one outfall or discharge. This reduces any objection there may be to sewage discharge to its smallest limits, and the Council will only have to provide for one septic tank and filtration plant. "The sewers should follow the most convenient route. Deep cuttings sho'jltl be avoided as far as possible, and the natural lay of the land used to the best advantage in laying the sewers. "Existing metalled streets should be left undisturbed where possible. Where there is a street metalled, such ai King street, trenching such a street should be avoided, as repairs are costly, and, furthermore, unsatisfactory.

"£BOO could be saved by the Council delaying construction of the sewers shown dotted red on plan, 'l'his amount u included in the estimate given. There would be nothing to prevent the Council undertaking the work at a later date. The line of sewer referred to runs from the junction of Queen street and Harris street along Helvetia road and Victoria street as far a3 Harrington ioad. The houses at the top of Harris street could be drained down West street. Provision is also made for connecting the sewers at the junction of Wfst street, Harris street and He lvetia road to one manhole, and providing tor the future extension of the Fchems up West street. "Consideration has been given to the possibility of utilising the existing railway cutting, this has been found to be impracticable for many reasons, the chief being: (a) The sewer placed c!o;e to the railway line would be damaged by the vibration . and woulj beccme leaky, (b) To avoid th;s it would have to be placed away from the formation and the Council would be Jaced with excessive side cutting, (c) Practically the whole length of the sewer in the cutting would be useless for Connection. It would he wdat may be termed 'dead.' It would ha considerably below the depth of the adjacent property, and connection therewith would be almcst impossible. Further, it would pass through an area not at present populated, (d) The railway department would require an inspector present on the work when any repairs m'ght be necessary, ana permission woull have to be obtained from the:n before any repairs could be effected. Delay in effecting necessary repairs may be cf serious consequence to the health of the borough, "The scheme I have submitted leaves practically undisturbed existing metalled streets; it follows the most convenient route, and tie size ot pipes and grades provided will avoid the danger of putrified matter lying in the sewer. The outfall is in the must convenient place and the discharge is purified in tha mo?t modern manner. The Council are no doubt aware that it is nust advisable to instal a drainage system before tha roads have been metalled. "Included in the estimate is 2000 feet of 6 inch branches and 1000 feet of 4 inch branches not 3hown on the plan. ESTIMATE OF COST.

"The sewer pipes should be large enough to car'y the drainage, hut small enough to be self-clean'ing. Sewer pipes larger than requisite lead to grave nuisances. "Uuttall f.honid be in most convenient place, and proper treatment of sewage provided, and the work should ba dons in a thorough manner.

" This is imperative and has had full consideration. No attempt should be made to lay 'cheap' drains. The work should be of the best quality throughout, carefully laid and supervisfd. Faulty drains are insanitary to a dangerous degree.

SCHEME SUBMITTED. "Levels have been taken throughout the whola drainage area and various preliminary schemes prep.?r3d; aa a result I have been able to provide a gravitational scheme with one outfall. The difficulty of contending with the fact of there being three watersheds in the drainage area has been overcome by the necessary cutting.

"Reference to the plan will show that the main sewer starts at the junction of Helvetia, Harris, and West streets, and is directed down Harris street until nearing Manukau road thence through private property past McGovern's house at the back of the hotel, continuing across King street through the Show Grounds to Edinburgh street, thence to Seddon street to the graveyard. The hill at the graveyard is avoided and the sewer is taken through the convent grounds to Seddon street, thence down the road through private property crossing the s'.rcam to the tank and treatment works; the sewer branches are til shown connected to the main sower.

j "Tha estima : cd cost of the whole | work, including main seser, sawer |to outfall, 9 inch, 6 inch, and 4 inch pipe sewers, anl msnhcles, lampholes, flushing manholes, ventilators, housa connections, septic tank and treatment works, acquiring land, engineering supervision and contingencies, is eight thousand five hundred pounds (£BSCU)." The Mayor said Mr Gannon had offertd to come up and go over the ground with the Council and explain the scheme He moved, That consideration be deferred until atter the Council had met Mr Gannon.— Carried. it was decided to meet Mr Ganncn, if convenient to him, on Tuesday.

"The position of the seweri follows the easiest and most con venient route; they avoid trenchinc King street while fully providinf for tha drainage of this most im portant business area. Brand sewers lie at the back of the pro per ties; by the latter crovision tht depth of sewer is minimised, thus effecting a considerable saving to the Council, and also to property owners. A further saving to property owners is effected by pipe sewen being adjacent to backyards. "Sewer connections to houses are allowed for in the estimate and may be laid contemporaneously with the sewer, "The sewei'3 are intended to be laid in a straight lice from manhole to manhole. "Junctions for house drains should be built in with the Eewers opposite every vacant allotment, and where not at present needed closed with plugs.

"Allotments now built upon will be connected from the sewer to tha boundary, no houße should bo directly connected to the sewer. "Communication should be made by a disconnector trap on tho property drained, and ventilation provided to the open air on the sewer side of tha trap so as to prevent the possibilities of sewer gas being forced back into the liou.'c. "All 6ewers shall be fitted with manholes, lampholes, ventilating and