DRAINAGE of GISBORNE.

Gisborne Times, Volume XXVI, Issue 2087, 13 January 1908, Page 3

DRAINAGE of GISBORNE.

MR.R.L, MESTAYER’S REPORT. SCHEME TO COST £125,000. proposed partial scheme. Tim Mayor lias received a report from Mr. It. L. Mestnyor, who was instructed by the Borough Council to go into the matter ol drainage lor Gisborne. TH£ REPORT . The report is as follows:—-“Sir,---In accordance with mstructions received from the Town Clerk, r fo furnish your Council with a report \ upon an extended scheme ol sewerM ;l g C for Gisborne, including the western end of the borough and the suburbs of Haiti and Whntuupoko, L liave had levels taken over the whole of the areas not included in mv learner report of May, 1901, and ha\o prepared a comprehensive scheme embracing the whole ol the specified have gone carefully into the matter, and after .reconsidering my former scheme, together with - '■ Hnv’s report thereon, X cannot see any- reason to deviate from my toimer conclusions, so far as the general principles are concerned, aluiouga in the scheme now submitted I ha\e materially modified some of the (le- ■ tails proposed in mv scheme ot I9UI. GENERAL PRINCIPL.Lt> Oh IHE SCLLI£MT£. i “Speaking generally, 1 julhero without any modification to the lollovvino- recommendations 1 then made, which I consider of primary importance, viz.: “1. That the town he sewered upon tho separate system, and that on ■no account should storm water from any roads, streets, or unpaved yards, be allowed to enter the sowers. . ' •. ' ~ i.o That in exceptional cakes tlie water from back roofs and paved vards in the more denseh- polluted areas may be admitted TniQ the sewers, but only if it cannot be otherwise dealt with without rendering tho premises insanitary. “3. That the water carriage system be adopted; and the pan system be abolished as soon as practicable. “4. That the Shone pneumatic system lie adopted to raise the sewage into the outfall sewer. “As the general principles of the scheme now proposed are identical with those I formerly recommenced, it.will be unnecessary for me to deal ■at any length with them in this 'report, and I shall confino myself to a description of the way in which I now propose to carry them into effect. The whole of the area to be sewered is divided into 14 separate ejector areas, of which nine are in Gisborne proper, three in Whataupoko, and two in Kaiti. These are all clearly shown on the accompanying plan No. 2, and on the lithograph, the boundaries of adjoining areas being differently colored so as to render them as distinct as possible. In view of the larger area now to be dealt with, I a propose to raise the sewago from the V different' ejector stations and deliver it into the head of an outfall sewer 21in in diameter, situated at the intersection of De Lautour and Wainmi roads: from this point the outfall sewer follows the Wainui road as far sis its intersection with Sponge Bay road, and thence it diverges southwards across tile flat ground at the foot of the ridge, through which it is taken in tunnel to the ocean side; from this point it falls quickly to the level of the shore, and is carried out .across the rocks and boulders to a point about two chains beyond tho southern extremity of Tuamotu Island, discharging into the ocean below low water. THE OUTFALLL.

“In my former report I favored passing 'the sewage through a. septic tank situated on the sand hills near the present sanitary depot, and discharging the effluent into the ocean at Poverty Bay; but now, in view of the greatly increased volume of sewage to be dealt with, the fact that a large portion of it will be much closer to the Wainui road than to the site orginally proposed for the septic tank, and that the cost of the outfall sewer will be chargeable against a much larger rateable value, I consider that carrying the sewage to the outfall at Tuamotu Island will be the preferable course to adopt. “On referring to my former report your Council will see that I have suggested the probable advisability of adopting this course if the suburbs were included in the scheme, as on page 14 of the printed copies. I say: ‘Should it be desired to include these districts (i.e., Whataupoko and Kaiti) some modification of my proposals ■would be necessary, and it would probably be found better and cheaper in the end to carry the main outfall sewer to Wainui. ... As the cost of such .an outfall sewer would be very considerable, roughly speaking about £IO,OOO, it would not, in my opinion, be suitable for Gisborne alone.’ “The proposed route of the outfall sewer was only decided upon after careful surveys of several alternative Toutes had been made by my assistant, Mr. Hughes, and I decided upon the present line as being open to the least objections. To have taken tjie sewer along the road past Mr. Nolan’s house would have involved an additional 22 chains of sewer, and a tunnel through very bad ground, and with an awkward bend in it; whilst to avoid the tunnel bv.carrying the sewer along tho beach would involve a serious risk of the sower being washed awav, as the sea is encroaching on tlie land at that point, and I understand that about 5 acres of Mr, Nolan’s land have been washed away during the last few years. Another site v/as examined some 55 chains nearer to the town, but as this would bring the outfall into—or very , close to—the proposed outer harbor, and would also have required .a very much longer tunnel, I did not consider it at. all suitable, more especially as the sewage would be discharged much'hearer to the shore, and would not be so readily swept to sea as at the outfall now proposed. SEPTIC TANK DISCARDED. “Mr. Hay in his report recommends that the sewage should not be discharged into the ocean without being first passed through a septic tank, and afterwards passed through aerating bacteria beds. This is quite unnecessary refinement, in my opinion, in view of the positiifn of ihe outfall, and I should not advise any treatment of the sewage, at least lor the present. If in the future it ptay Appear that there is any likeliaocil of a ‘nuisance being occasioned, it •would be quite easy to construct a septic tank below tho outlet end of the tunnel, and pass the sewage through it before discharging it mto the ocean. . “Under no circumstances, ionover, do I consider that aerating beds would be required, judging from the '.working of other septic ranks I lirye constructed, and the fact of the d’.scliargo occurring into pernnuont v liter at low tide. THE POWER STATION.

"I propose to place the power station on corporation land at the intersection of Oliiklers-road and Cnrnar-von-stroet, in what is now used as tho corporation yard ; this is more convenient for tho air mains than the site first proposed. The power is to ho supplied by Diesel oil engines, as suggested by r. Hay* this being trie tmost economical typo of oil engine known. As an alternative, a power gas plant might bo installed, but .1 have not been able to obtain sufficient information as to tbo economy of this installation at present; I ha.ve written to England for particulars as to the first cost, and cost of working with power gas. This is, however, a matter of detail which can be decided upon later, as the amount included in the estimate for power will be sufficient for gas or oil. The gas plant will, however, take up considerably more space, in connection with the power required, I. may refer to a point upon which there is a difference of opinion between Mr. Hay and myself. Mr. Hay considers that I have underestimated the amount of rain water which will come into the sewers from house roofs, etc.; mow this is a matter which is entirely within tho power or your Council to control, and if my recommendation *fo 2 be- rigidly adhered to, .so far

from any original estimate being too low, it woull bo found that tbo quantity may easily bo reduced to less than two gallons per head per hour, except possibly in the two central areas. As the whole of the sewerage will have to be •raised, it is of the utmost importance to your Council that tho .amount of rain water so introduced should be restricted to Llio minimum, or the annua cost, ol pumping will be much higher than u INCONVENIENT connections. “There are some sections in tlio town which lie at a lower level than that of tho adjoining streets, ami there will be great difficulty in connecting houses built thereon witn tho sewers unless some means are adopted to raise the ground. J nmlerstaint that there are a few old bouses at present in existence in such positions, but. 1 do not consider if ‘‘quitable to burden the whole ol the ratepavers with the cost ol putting in exceptionally deep sewers to meet a few isolated cases. The scheme will he quite eost-lv enough as it is \Mtlimit so doing, and the proper course, in mv opinion, will bo lor your Council to refuse any permit to build on ,uoh low-lying ground until it has been filled m to the level of the street into which the houses have to he drained. In the case or houses now built in sueli positions that they cannot be connected wit'll the proposed sowers, it mav bo found necessary either to call upon the owners to reconstruct their conveniences at such levels as to enable connections to 1)0 made, or to continue the present svsiem of night-soil collection until tho premises can bo altogether re-built at a higher level. This will not bo quite as objectionable as-at first- sight may appear, because some portions ot the town are so sparsely built upon that it would not be advisable to sewer them at the present time, and in these the present system of collection will have to continue until sufficient houses are 'erected to justify a further extension of the scweis. lienee it will not be possible to totally abolish the present system immediately, and probably by the time that this can be done, the difficulties attending these houses may be removed. An mv former report 1 mentioned that owing to tliq great depth of some of the sewers a double line of pipes—a high and a- low level line—■ would be required; in the present scheme, by remodelling tho ejector areas, most of these difficulties have been overcome, and only in one oaso —part of Herbert-street —will a double line be needed. It has been necessary in some cases to carry tho sewers across private property, but I have only done this where unavoidable. or where the conditions rendered it practically essential. I estimate that the total cost of tho scheme will amount to £125,000, as shown on the annexed detailed schedule; but as there are large areas upon which no houses are yet erected, and which will, in ail probability, not oven be subdivided for building purposes for some time to come, it will be unnecessary to raise anything like this ount at first. Areas Nos. 5,6, 7,8, and 12 may be omitted altogether for the present, and in areas Nos. 3,4, 9, 13. am! 14 it will not bo necessary to commence with more than onodialf of the sewers which will be ultimately required. Also, the total power required will be about 120 b.h.p., but it will be sufficient to start with a pair o: 40 b.h.p. engines, and a third engine of SO b.h.p. can bo added in the future when there is.sufficient sewage to render the addition necessary; there will then bo the full power wanted, together with a reserve in case of accident to one of tho engines. The engine-houses, also, can be constructed to hold only the engines first installed, and bo subsequently enlarged when additional power is required. COST OF SCHEME FOR POPULATION UP TO 12,00. On this basis, I estimate that £83,000 will bo ample to carry out. the work which will be required until the population amounts to about 12,000, uid other areas can be included from time to time as increase of population may render necessary, without In any way interfering with completed work or any interruption to the regular flow, of' sewage from those areas first connected, to the outfall. The estimate of £83,000 provides, for the whole of the outfall sewer being constructed of the capacity which will be ultimately required for a population of 30,000, and I consider that it will be necessary to carry out this portion of the work to its full capacity from the beginning, as the amount of fall available to the entrance of the tunnel is sufficient to ensure a. selfcleansing velocity in a smaller-sized nipe. GENERAL REMARKS.

“All the iron and steel air and sewage mains to and from .the various ejector stations must bo of their full capacity from the beginning, as any future modification of them would involve throwing one or more of the stations out of work. In order to reduce the cost of these mains to a minimum, I have provided for all pipes of six inches in diameter and over to be spiral riveted steel pipes. “The estimate provides only for the actual cost of the work itself, but the amount of the loan to be raised should be in excess of this to provide for the cost of raising the loan and tbo payment of the first year’s interest, wlrch latter is usually paid out of the loan moneys. The amount to be allowed for these purposes will depend upon the actual amount raised, and will be a matter for the consideration of your Finance Committee, hue I merely wish to make it plain to your Council that any amount required for any purpose other than the actual construction of the main works must be added to the foregoing estimate. Provision must be also made for tho right of easement or purchase of land traversed by the. outfall sewer. The probable amount to be paid for this right can be mere readily ascertained by your Council. I was informed that it would be onlv a small matter; but whatever the amount may be, it should be tb finitely ascertained before the loan is sanctioned, so as to be included therein. The cost of taking sewers across private property will not .bo a serious matter, and be 'met out of the 10 per cent, allowed for engineering, legal expenses, and contingencies, as in the case of ail action for compensation brought against the Wellington Corporation the Chief Justice ruled that no compensation for easement was payable whore the houses on tho property were directly connected to tho sower traversing it, the only compensation in such cases being for the actual damage done to the ground, gardens, etc. THE PEAKS. “Three plans accompany this report, viz:—No. 1. A lithograph map of tlio borough to .a scale of 10 chains to one inch, colored to show the ejector areas, positions of ejector stations and power station, and the distribution of all the air and sewage mains from i lie ejectors. No. 2. A plan to a scale of 5 chains to nil inch, on tracing-linen, colored to show tho above particulars. and in addition tho distribution of all the .stoneware pipe sewers. Also, to a scale- of 10 chains to aa inch, tho plan of the outfall sewer from Dc Lautour road to tho outfall at- Tuamotu Island“lt must bo noted that m areas Nos. 5, G. 7. and 8, on plan No. 2, only the main lines of sewers are shown, there being no information obtainable as to tho probable mtimato subdivision of the land; but tlio sewers shown are designed at such grades as will enable the sowers in any -new streets to be connected therewith; and the estimate includes the cost, of such additional sewers, manholes, and lampholes as may be required for such streets, judging from a comparl- ' son with those required for other areas which are fully subdivided. “1 believe that in the foregoing report I have fully covered the ground ■required to put the matter clearly before your Council, but should there be any point which I have not undo quite clear, I shall be pleased to supply any further information _ in mv power on receiving intimation to that effect- from the Town Clerk. ESTIMATE OP TOTAL COST. Outfall sewer, including manholes, tunnel, and extra work crossing from mainland to seaward side of Tu a mot u Island £14,700 0 0

Reticulation sewers, Gin, Biu, Din, and lOin, stoneware pipes, manholes, etc. 52,0 bu 0 0 Fourteen ejector stations, wit'll ejectors, valves, and nil fittings, finished and erected complete; also omergeiic.v outlets to river...2o,U U Air aml sewago mains, of east- iron and steel, including valves laid and fixed complete 19,900 0 0 Power station, work- „ shop, and tools 2,000 0 0 Air compressing engines, with air compressors, compressed air receiver, and all connections 4,500 0 0 £1.13,700 0 0 Engineering, supervimv.'i, legal expenses, and contingencies, 10 per cent, 11,3< o 0 0 Total 0125,070 0 0 Say £125,000 0 0 THE MAYOR’S VIEWS. SCHEME SHOULD BE CAREFULLY CONSIDERED. THE STORM-WATER PROBLEM. With a viow to ascertaining lmw the report on the drainage scheme for Gisborne was received, a reporter waited on his Worship the Mayor. Mr. Towntey stated that as the plans had not been received from the Post. Office, it was difficult to decide the matter from the report. However, lie said that the scheme was on the same lines »s,ilr. Mestayor’s previous report, but it was more extensive. The complete sewage system was to cost £125,000, but in addition to that the house connections would cost between £IO,OOO and £15,000. Recently. Tininru bad to raise a loan of £IO.OOO for the latter purpose. Judging from the statements of Mr. Hay’s report, it seemed the only leasi life scheme, although it was a big undertaking, and should be very carefully considered by the Council ami the ratepayers. He was glad that a septic tank was being dispensed with. The sum of £83,000 would ensure drainage for some years to come, say ten at least. He had not vet seen the plan showing what sections the £83.000 alternative seliemo cut out. The working expenses and machinery would- be a very considerable item, and £IOO,OOO would be the smallest sum to start tho scheme with. Ho made it clear that this scheme, even the complete one, was for sewage only, and stormwater would also have to be provided for. If it was allowed to enter the drainage system it would clog the drains and silt up, thus entailing extra pumping. This scheme would leave us exactly where we were in regard to stormwater and household' water and waste. The ratepayers would liave to pay for it, and it produced no revenue. Mr. Townloy pointed out that those portions of the place not in the drainage system would still require the continuance of the nightsoil 'contract.

INTERVIEW WITH MR W. D. LYSNAR. SCHEME TOO EXPENSIVE. DRAINS SHOULD GO EVERYWHERE. WELLINGTON’S EXPERIENCE. ■STORMWATER. CANNOT BE SHUT OUT. Mr. Lysnar, interviewed said that the Shone system was beyond tho reach of this borough for a very considerable time. Mr. Mestayer’s first report provided for a scheme to cost £39,250, which was for a part only of tho Borough proper. He gave an estimate of the annual cost of pumping at £IOBO. This capitalised at 5 per cent, came to £21,000. Under the new scheme the initial cost was to be increased to £125,000, but Mr. Meslayer did not say how much tho annual cost of maintenance would be, and until that was known lie (Mr. Lysnar) was not in a position to gauge tho full extent of the amended report, but it must cost- more to run than-the wrevious one,' which was £IOBO, but if only that capitalised was added, the sura required would be £146,000, and it was absolutely beyond the reach of this Borough. Regarding the alternative suggestion to cost £83,000, it was impossible for him to express an opinion on it, as he did not know .the areas proposed to bo excluded from the benefits of the scheme, and no scheme would be fair that did not include the whole of the present settled portions of our Borough. . This 1 was the position ho took up with this and with the present water supply, and maintained throughout. , Ho always felt very strongly on the Shone system, suggested by Mr. Mestayer. It was quite impracticable for this Borough and too expensive. This system was installed,at Wellington, and before it was properly installed Mr. Lysnar understood that tlie ratepayers had to be called on for an additional loan of £30,000. This was mainly in consequence of there not being, allowance made for pumping sewage during periods of wet weather. It was 'found utterly impossible ' to completely shut off the stormwater, and for that rea,/>n Wellington had to go to a, much larger expenditure than was anticipated. ‘ This might do for Wellington, with a population of 70,000, but a population like ours, between 6000 .and" 7000, could not entertain such a costly system. He did not consider that drainage was a difficult matter for this town, and it would be possible to provide an efficient drainage scheme that would servo us for the next ten years or more at .a cost well within reach of the Borough; but that- could not be done on tho Shone system.

CONSIDERATION BY THE COUNCIL.

The Borough Council meets to-mor-row night, when the drainage report will be brought up.