THE SEWERAGE SCHEME.

Nelson Evening Mail, Volume XLIII, 18 December 1909, Page 4

THE SEWERAGE SCHEME.

CITY ENGINEER REPLIES TO THE HEALTH DEPARTMENT. ADJOURNMENT OF DISCUSSION. A Special meeting of the City Council 1 was held last evening, to consider the I report from the Health Department on tile city sewerage system, and to re- j ceive a reply thereto from the City Engineer. There • were present the Mayor I and all the Councillors. The City .Engineer presented the following reply to the criticisms contained in the Health Department's report ; — . "In response to a. resolution passed by you at your meeting of the 10th inst. that I should submit to you at this meeting my reply to the report furnished by Dr Frengley. on the. new system of sewerage for the city, I beg to state that I have given it my very <areful consideration, and find it to contain severe strictures and serious allegations against myself and staff, and also against the Department's own inspector. It would not be unfitting at this stage, gentlemen, to inform you that in dealing with Dr Frengley's report I will do so in a fair aud impartial spirit. Where I consider his remarks are correct I will have no hesitation in supporting them, and where 1 consider them to be inaccurate I shall deal with them in a' manner befitting such inaccuracies. As the report is the product of two men (Dr Frengley and Sanitary Inspector Middleton) it may in some cases in my reply be necessary to make the singular include the plural. In the opening section of the report it is stated .that a manhole in front of the Anchor Foundry (Wakefield Quay) was visited and opened, and it is asserted that it is suitable for its intended" purpose so far as cleaning out the drains with Tods is concerned. Surely they must know that these manholes, serve a dual purpose, inasmuch that not only do they provide means for gottinjj^down to tile sewers for cleaning purposes, but they also provide an inlet for fresh air to the sewers through the elongated openings in the cover, the presence of which the report appears to take exception to, and which are alluded to as cavities. In the same paragraph the report goes on to state that the liquid in the manhole invert was about two inches in depth. This is a matter I would not dispute, as it is a very difficlt matter for anyone standing on the surface looking down a narrow shaft 10 feet in depth to guess with any degree of accuracy the depth or composition of any liquid flowing at the bottom, biit I do know that I have measured it under practically similar conditions' and found the depth of sewage to be I inches. "In section. 2 it is pointed out that, at the manhole at Russell-street the flow from Wakefield Quay still continued in the same volume (presumably as that noticed in front of the Anchor Company's Foundry). Now, this must mean either j one of two things .either that there was not 2in of sewage in front of the Anchor Company's, or there must have been more at Russell-street, because the pipe that Mr Middleton has evidently mistaken for the Wakefield Quay and Haven-rd west sewer is the inlet from the collecting chamber which (with the exception of three houses in Russell-street) receives the whole of the sewage from that area bounded by Britannia Heights on the south, Maori road on the east, and Mary Ann street on the west, a goodly adzed area, with a fairly large number of connections. "In commenting on the ejector station you are informed that it contains an ejector of 100 gallon capacity, and that the walls wero not altogether free from moisture. In regard to the moisture on the walls, it must be fully recognised that the walls of any subterranean chamber will always sweat, which must apply in this case, as the only portions of the j walls that could bo seen from the surface are- five feet abov e saturation level, and 1 am quite sjuro Mr Middleton never descended into the chamber, or he would have found that there were two 100 gallon ejectors installed, and not only one ps ho asserts. 'In regard to section 3— in order to j make my reply as cohorent as possible I will allude to it in conjunction with sec- '■ tion 10. "In section 4 the report states that Collingwood-street ejector No 3 was receiving and discharging at a rapid rate. ■ This statement is quite correct. I will I allude to the cause of it at a later stage. I would here point out that this station is also fitted with two ejectors, and not only ono, as Mr Middletou'a remarks would convey, and that the manhole cover is a plain hinged ca6t-iron cover s without any openings in it whatever,, as Mr Middleton asserts it has. The sea water gains access to the chamber round the edges of the cover, which are not . tight fitting. It is not really necessary 1 for these chambers to be ventilated,- as they are fitted with air scour pipes con-

mmmmmm —__»^-^— — a— ■— — — — —— necte dwith the preuurs main end conti- | nued to the bottom of the chamber in ' order that before anyone enters the chamber he may turn on the air peß- , sure and Jill the chamber with pure air. j "Section 5 will be dealt with in con- ; junction with Collingwood-street and j Cambria-street. "Section, 6, ejector station No. 2, Vanguard and Hardy-streets. — This chamber contains two 160 gallon ejectors. The water in the bottom noticed by Mr Middleton was in the collecting sump situated immediately under th e manhole cover, and not all over the floor as the report would imply. It is quite correct that the Vanguard-street south flection was delivering a good flow of sewage, which, is later on in the report alluded to as reasonable. As a matter of fact this manhole receives sewage from a fairly large area, one of the best drained in the city. . "Sections 7 and 8 will be dealt with in conjunction with Dr Frengley's comments. "The first paragraph of section 9 will be dealt with in conjunction with section 14. "In tho second paragraph, of section 9, alluding to the receiving chamber in Collingwood-street, it is stated that the sewer was discharging a volume equal to^about four-fifths the area of the pipe, although tho same pipe was full a few chains higher up thc street. Surely Mr Middleton would not have you believe that because a pipe was full at its inlet thai it should also flow full at the. outlet, especially when there is provision mado for an increased velocity at thnt outlet. I should not have remarked on that point had it not been for the inference that thero was something in the sewer impeding the flow to that extent. It is also stated that the j Weka-street sewer was discharging about | three inches in depth intothe same manhole. A small-study of .the position would have,ic6nvincj__ lim of-the cause. As he has evidently overlooked it.- 1 v.-ill make mention of it for your inf or mat inn. It is well-known that tne ejectors work alternately with certain periods of rest between each discharge. When the liquid to be dealt with comes m to the manhole in fairly large quantities as it does in this case, there is always an accumulation in the manhole between the dischargers, and as there is very little difference in the levels of Collingwood-street' and Wainui-street inlets, the sewage will naturally back up into • Wainui-street for a good distance, owing to the, flat fall in that street. Consequently, when neither of the ejectors was receiving its nex* charge and the manhole emptied again t_ •invert level ,the backed-up sewage would return again through the manhole to the ejector. "In regard to sections 3, 10, and 11, Cambria-street, I quite concur with the report that the condition of things from} Collingwood-street to about a chain eastward of Tasman-street is undoubtedly defective, permitting sub-soil water to enter the sewed. This matter, has been receiving attention for some little time. Several defects have been found and remedied, mainly ■ broken pipes. These pipes hav_ been broken by careless ftlling-in, as the sewer was tested with a five-feet head water pressure under the supervision of Inspector Dorizac. ... "Section 12.— 1n regard to the manhole at the junction of Milton and CambiSatbtreets. the only ,-reason. of flushing from this is for the purpose of cleansing that flat portion of the sewer between Milton and Tasman-streets. Nothing accumulates in that manhole that would necessitate flushing on ite own account. "Section 13.— 1t is stated in this section that at the junction of Milton and Bridge-streets, also Milton and Hardystreets, the 8-inch sewers did not contribute sewage of a greater depth than cne inch. I might point out that the measured flow at these points has never been found to exceed the depth stated, but the pipes are six inches in diameter and not eight inches as stated in the report, which means a very different thine when the comparative wetted perimeter of the pipe has to be consider "Sections 9 and 14.— Ejectors : When I dealin, with section 4, I intimated that I would again refer to it m connection with section 14. In reference to the rapid discharge of the ejectors in the Collingwood-street station, this may be the result of three causes. When Mr. Mcstaver was bore in January last he laid down certain methods of testing for leaks which were to be conducted over a given section. These tests were to be carried, out at certain intervals, and necessitated stopping out the section to bo tested. Consequently th e sewage at the back of such section backed up for i a considerable distance during the period of carrying out the test, so that when this backed-up sewage was relea?ed it would naturally give the ejectors much additional work for the time be-

i -. .-."- *r«o(>»=.>-- - . " ing. The same thing applies to flusn- ' ing the sewers. - This work is not. done as many no doubt think, i.e., by simply putting the hose in a manhole and turni mg on the water till the flushers think 'it has had enough. The modus operan- '• di is this: The inlet to the manhole I above the section is plugged, and the men then fill this section from the main, afterwards withdrawing the plug, allowing the accumulated water to suddenly rush through the section to be flushed. This would again give the ejectors extra work for the time being, and I think I amj safe in saying that the quantity of water used in this way ig in excess of what the sewage will be when the whole of the connetcions are completed, inasmuch that it does not take a very great quantity- of water to keep the solids travelling, but once they stop and accumulate, it takes a fair' body of water to start them again. These causes .together with the leakage in Cambria-street, will account for the speed at the Collingwood-street ejectors. Taking the number, of houses in the Wood area connected with tha sewer, the estimated flow of ■ sewage should not exceed 86,000 gallons a day When the report states that 196,000 gallons pass through the No. 3 ejectors this is no doubt an exaggeration. Mr. Middleton admits that he has based his figures on a 21 jnjnutes' observation. From my knowledge of the efficiency of the ejectors and repeated timing, together with gauginga of tho discharges checked separately from the other stations, the discharge during the winter floods did not exceed 132,000 gallons, a day, which noints out that 46,000 gidlons a day of sub-soil water was finding its way into tho Cambria-street, sewer, betweert Tas-man-street and CollL-gwopd-street. On blocking out this section and letting the sewage tises in. the manhole and flow through Tasman-street .and WekaBtieet, the flow fell to what may be estimated to be practically normal. Dr. Frengley remarks that 50<,gallons a head a day may for Nelson be regarded as the maximum use of the sewers. 1 might point out that during the winter months, when there is- no street or Harden watering, the average consumption a head is 93 gallons, so on that basis I think about 60 gallons a head may find its way into the sewers. "Septic Tank.— Dr. Frengley states in his comments that on yisitmg the septic tank he found, the by-pass open and the sewage passing . direct to the harbour. Thfs was so ; .diluted sewage was passing into the main outfall and delivered into the waters of the bay at a point over three-quarters of a mile from the septic tank. I was ""aware that the valve had been opened, but l afterwards ascertained the reason for it During the winter months, when repeated floods and heavy tides prevailed, which completely submerged several of the sewer manholes, much water found its way into the sewers. Ihe ejectors, especially Nos. 2 and 3, were very heavily taxed, and were required to deliver large volumes of water Bemg as well aware as. Dr. Frengley that --i square yards of straining medium consisting of material varying from 4in. and 6in. in -eize to small pea gravel was not designed for and could not possibly pass the, requisite quantity ot water, it was foond necessary at tunes to open the -by-pass to permit of these flood waters being delivered, otherwise than, through the tank. . On two occasions the tank ' did overflow, washing • away a portion of the unprotected bank before we could get down to relieve it. i Another reason for by-passing is that ' while effecting repairs to Cambria-street it still becomes necessary to carry ■ on flushing operations, and if at such I a time the surface pump on the repair- • ing works goes wrong, then we have to ■ resort to pumping out the trench with ' the ejectors rather than let the water ' rise and damage the work. This is what ' had happened when Dr. Frengley visited . the tank. Another reason for by-pass- • ing at intervals is that as the valve is ' about two feet back from the face of t the chamber, this length gets filled with 1 solic*. matter, which if not relieved be- - fore it sets hard becomes very difficult to shift; therefore the valve is opened 1 for a few minutes on different occa- ' sions to relieve this before it has the opi portunityto set. The reason the sewage in - the screening chamber was 2J inch, be- - low the crest of the aerating weir (not ' 4 inches as Dr. Frengley states) was due • to the fact that it becomes necessary ' to work the sluice valves at intervals in r order to prevent it sticking. Thisopera- " tion is carried out during ebb tides, ? and to it no" doubt is due the fact that 1 the tank effluent was below the crest, ' as this was done when the by-pass was 1 opened the day before Dr. Frengley's r inspection. "Continuing, Dr. Frengley states that t the sewer in Cambria-street is defec- - tiye. I was perfectly aware of this. s Bofore his visit this defect had been - discovered by me, and the work of effecting the necessary repairs put in hand. In regard to the other manholes and streets mentioned by him as being "flow reasonable," "reasonably good," "oonditions within the normal," etc., these remarks are undoubtedly am r biguous. Witb all respect to Dr. Frengley, I would like to know how ie arrived at this decision, for there is not the slightest doubt in my mind . that he is totally unaware of the number of houses connected with the various sections or whether the sewers are laid in wet or dry ground. "In commenting on the old Bewors, it is remarked that- there is just as much sewage coming down by the oldsystem/ as the new. Here again the doctor is correct, as there are more services connected with the old than with the new system. The doctor in his concluding remarks states that it is impossible to have" any effective systeni with such evidenc of extremely bad con- ■ struction and indifferent supervision in parts thereof. I will deal with this j in connection with section 5 of his remarks. Section 2. — In ''this connection the matter of by-passing the sewage into the waters of the bay over three-quarters of a mile from the tank is again dwelt ( upon, etc. It would be interesting to know what further demonstrates the probability that this has been going on j for some time. .. I have already stated i that it has been done when occasion de- i manded it. On the question of analysis, I am quite prepared to accept the doctor's euperior knowledge on those points, as ■it would be absolute arrogance on my part to question them. Continuing ,it is stated that "in view of these results it is not surprising to me to have heard it said in Nelson that near the foreshore offensive smells are frequent." Surely the intermittent by-passing of diluted sewage to a distant point, which becomes further diluted (it is safe to sav) to the extent of 100,000 to one, it not going to be blamed for that. I also notice that danger is apprehended from this source in connection with the oyster beds inside tha Boulder Bank at Lighthouses Point, and the doctor supposes the facetious contention is advanced that the sewage is being treated before it entes the harbour. The matter of oysters has nothing to do with this Council, and I should not have alluded to it had it not been sandwiched in with the septic tank ahd by-passing the sewage and holding the latter out as a further menace to the public health. The facts axe, as I happen to know after careful and repeated " current observations, taken duriny varying states of the tide and winds, backed up by local knowledge, afforded by men who have been boating in the harbour for years, and having good cause to study the currents, it was

discovered that the water conning into th* harbour up the south -channel never crossed the middle bank on the ebb tide bnt set straight out again past' the Government Wharf.' That is why '■ Dr. Mason permitted Merlino's oyster beds inside the Boulder Bank at Lighthouse point. '„•_■ "In the first paragraph of section 5 I have no doubt that Dr. Frengley is correct, but in the second paragraph it is stated that -on account of bad construction and insufficient supervision sub-.soil water has not been adequately kept out in Cambria-street, and he fears that smaller leakages will be found elsewhere in the Wood. In regard to the alleged bad construction and inefficient supervision, I may state that 1 visited the work from time to time myself, and there was also a works superintendent and a ganger, and m addition the Health. Departments own inspector spent a great deal of time on this section, apart from -the work of carrying out the necessary tests. "In regard to Dr. Frengley s recommendations to his Department, and to the Council, I consider those outside the scope of nw leply to his- report. "Conclusion.—ln submitting to you this reply to the criticisms and^strictures conveyed in Dr. Frengley's report, I have foud it necessary to correct certain obvious erroneous remarks made by him. I have no doubt that the cause of such remarks and the degree of supposition that he has found it necessary to indulge in has been due to the fact that it was utterly impossible for. him to become better acquainted with all details of the question owing to ; the limited time at his disposal and ofl the Whole I don't think his report, when corrected, conveys to tho public anything they were not cognisant Of before. The doctor complains of the indifferent supervision, a point that I do not admit, for as a matter of fact it does not matter how good the supervision the workmen will beat the supervisor sometimes. In the case of sewers this can only be found out by testings, and I would point out that the rr^ftjor portion of this work, including Cambria-street, was conducted by the Department's own officer, and the subsidy to the Department for his services, together with his assistant's wages, cost this Council over 300 per annum. I might also point out to you that the report is the production of gentlemen whose knowledge of any- engineering, construction must by their calling in life or professions, be limited to an extent. It is only consistent with rea^ son that any engineering work can only Be criticised by anyone possessing a thorough knowledge of the subject before him. . This point affects both Mr. Mestayer and myself. Mr. Mestayer in his report of February last expressed himself perfectly satisfied with everything that had been done, with the exception of the deep sewers in the Wood, i.e., Cambria-street, two sections, and laid down certain tests to be done to ascertain the leaks. Therefore 1 would rospectfully suggest that either he or some other gentleman who by virtue of his special professional training, is competent to express an opinion, should make an exhaustive examination of the system, and submit to your Council an- exhaustive and comprehensive report." The Mayor moved that the report be considered on January 7th. They should go through the report carefully before discussing it. Cr. Turner seconded pro forma, but thought they should go on with the discussion of the report. They knew as much about it then as they would know in six months' time ; and everyone knew the condition of things in the Wood. ' Cr. Field said they could have some discussion. There were a number of "matters connected with the Health Department's report that they might easily look" into. They had spent £300 a year to the Health Department to inspect the work. What did th e Department inspect? The Council placed the supervision in the, hands of the Health Department. The Department did so and gave certain reports. One or two of the reports at least were very satisfactory* - T, • ' The Mayor said that Mr. Donzac inspected some sewers on his own account.' Afterwards Mr. Dorizac was appointed • inspector by the Health Department, i A resolution moved by Cr. Grace on April 15, 1908, was read, was to the effect that the Health IJe- j partment be asked to supervise and di- , rect tho testing of the sewers and ajr • mains now laid, and as they are laid I . down, either by the smoke test, the nyi draulio test ,or both. i Cr. Field pointed out that it was on . December 27, 1907, tbat the question of • day labour first came out. In March . or April the Medical Association wrote i to the Council drawing attention to the ■ testing of the sewers, and the Council then definitely asked the Health Depart- • ment to inspect .the services. The L»e- ■■ partment consented, so that since then if there was any blame it was the Department that was to be blamed. The Health Department's Teport 'on testincr was read. This did not include Cr Pettit said that at the tune he pointed out that the Wood area, in which the leaks were, was not dealt with, and he had been o™^ nnderstand that a Teport on the Wood area would follow. W Health .Department should be written to and asked "-hy iurther reports wero not furnished as requested by the Council, and why the W^od area h*d not been reputed on previously. The only, reasonable flung to do was to ask Mr Mestayer to report on the work. Commonsense dictated that the man who designed the ■•-ork was the man they should now call The Town Clerk said that two reports had been received from the Health Department. , _ Cr. Turner was opposed to this. Jiew could Mr. Mestayer tell what was under ground? It would be only a waste of monev to get Mr. Mestayer over. The Mayor said that they had known phout the leaks in the Wood for some time. All the Council had to deal with was in connection with Cambria-street, and he did not want any more experts. Cr. Grace did not want to discuss either of. the reports that night. He waa not at present prepared to say what the Council should do. The Engineer should get a report from an impartial sanitaTy engineer. Mr. Mestayer, as the designer, would be biassed to some extent. It would be mjoney well spent to get the best engineer in the Dominion to give them a report. The Mayor's motion to adjourn further discussion till January • 7th was then carried on the voices. __ It was resolved that a copy of the City Engineer's report be handed to the press for publication. • _ \ In- reply to Cr. Grace, the Engineer said that "a sower could be tested after it was laid and covered in.. » Cr Field thought the Councd before carrying the Mayor's motion should have decided to write to. the Health Department for further information.