Some Notes Descriptive of the O'shannassy Scheme to Supplement the Melbourne Water Supply (Paper & Discussion)

PAPER—NOTES OF THE O'SHANNASSY SCHEME. IO5

Institution of Naval Architects—Index to Vols. XLVII. to LIV. Monthly Summary of Australian Statistics, No. 18, for June, 1913. The Canadian Engineer—Weekly Nos. to 21/7/13. Revue d' Electricite—Vol. XIX., Oct., Nov., Dec. 1912, tsos. West Australian Institute of Engineers—Vols. I., II., III. Engineers Club of Philadelphia—Vol. XXX., Nos 2 and 3. Report of Engineer-in-Chief for Railway Construction for year ended 30/6/13. Commonwealth Census Bulletin, 30—Population and Vital Statistics. Western Society of Engineers—Constitution and List of Members. Associazione Elettrotecnica Italiana—Vol. XVII., Nos. ic, II, 12. Electrotechnische Zeitschreft—Weekly issues to 10/7/13. Societe Belge d' Electriciens Proceedings—Vol. XXX., Feb., March, April, May, 1913. Smithsonian Institute—Annual Report for 1911. University of California—Chronicle, Vol. XV., Nos. i and 2. Journal of Agriculture—Monthly Nos. to 5/5/13. Mining and Engineering Review, Vol. V., No. 59. North of England Institute of Mining and Mechanical Engineers—Pro- ceedings, Vol. LXIII., parts i, 2, 3 4, 5. Society of Engineers—Transactions for 1912. American Society of Mechanical Engineers—Transactions, Vol. 33. Institution of Civil Engineers, London—Vols. 189,190. Harvard University Journal, Vol. XI., part 4. Macsachusetts Institute of Technology Bulletin—Vol. 48, No. I. The Franklyn Institute—Vol. CLXXV., Nos. i to 6, Liverpool Engineering Society—Transactions, Vol. XXXIII. (1912). Department of Mines, Victoria—Bulletin No. 28, with Maps. Royal Victorian Institute of Architects—Vol. XI., Nos. 1, 2, 3. PURCHASED ; Morris : Steel Structure. Rea : How to Estimate. Frye : Civil Engineer's Pocket Book. Gillett: Cost Data.

The HON. LIBRARIAN particularly desires to draw attention to the three volumes comprising the pamphlets and papers issued in connection with the recent International Road Congresses Asso- ciation (1913).

PAPER.

INTRODUCTORY.

The PRESIDENT introduced Mr. E. G. Ritchie, Engineer to the Metropolitan Water Supply. He had also the pleasure of intro- ducing Mr. Ritchie as a new member of the Institute. He thought it was a good augury of Mr. Ritchie's future utility to the Insti- tute that the first occasion upon which he was able to attend as a member, was also the occasion for which he had found time and energy to bring before them such an instructive subject as the Io6 VICTORIAN INSTITUTE OF ENGINEERS :

O'Shannassy water scheme, upon which he was so well qualified to speak. Mr. E. G. RITCHIE said he had first of all to thank the Presi- dent for the kind remarks he had made. He was glad he had been able to do something of service to the Institute so early in his membership. It was a pleasure to be able to do it, but of course there was a difficulty in getting time for that sort of thing, as the work of public servants was very strenuous. However, he was very glad he had been able to do some little thing. In speaking on the subject before them he was taking it for granted that the majority of those present knew the main features of the Melbourne Water Supply. There was not much time to go into the subject and describe the existing system to any extent. They had two distinct sources of supply—Yan Yean system to the Yan Yean storage reservoir from the waters of the Plenty River and Jack's Creek. The water was brought a distance of 41 miles to the Preston Reservoir. The Maroondah system was 41 miles from Melbourne, and also concentrated into the Preston Reservoir. There were three distinct means of communication—one from the Yan Yean Reservoir through the open channel and pipe heads and Preston Reservoir, and thus to Melbourne; secondly, the Maroondah aqueduct, by means of which water was gravitated into the Preston Reservoir; and thirdly, the Yan Yean to Surrey Hills high level main, to which the water was supplied from the Van Yean for the service of the eastern suburbs. The Maroondah aqueduct, at about 3z miles out of Preston, was loo ft. lower than the Surrey Hills Reservoir, therefore any water brought in to the latter could be delivered to the Preston Reservoir also.

SOME NOTES DESCRIPTIVE OF THE O'SHANNASSY SCHEME TO SUPPLEMENT THE MELBOURNE w WATER SUPPLY. By E. G. RITCHIE. HISTORICAL: The proposition to divert the head waters of the Upper Yarra (including its most important tributary, the O'Shannassy River) for the purposes of the Metropolitan Water Supply, was first mooted in 1888 by Mr. W. Davidson, M.Inst. C.E., Engineer of Melbourne Water Supply at that time. PAPER—NOTES OF THE O'SHANNASSY SCHEME. I07 Mr. Davidson then estimated that the Yan Yean and fully completed Maroondah scheme would be entirely required to serve a population of about 700,000 persons. To provide for further population he recommended the Government to reserve some 115,000 acres of State forest at the head of the Yarra for water supply purposes. His efforts were successful, and it is fortunate I w that he showed so much prevision for the needs of the metropolitan community, as water from these sources has become a vital necessity for the metropolis, even before Mr. Davidson anticipated. The present population is estimated at 628,000 persons. It had been intended to enlarge the present Maroondah conduit from 25,000,000 to 50,000,000 gallons per day capacity, and to construct a storage reservoir of 2,000,000,000 gallons in the Maroondah Valley before tapping the waters of the Upper Yarra. The abnormal growth of the metropolitan population to the east and south-east, and its comparative stagnation on the western and northern sides were the factors which made it necessary to recast the whole position. To provide for every possible and probable development of the higher levels of the eastern and south-eastern metropolis by a gravitation supply it was deemed expedient by the Metropolitan Board of Works to carry out the first step in the Upper Yarra scheme by a conduit as far as the O'Shannassy River, before com- pleting the Maroondah scheme. This action was necessary because the Maroondah aqueduct would not serve the higher levels referred to except by resort to pumping, which was undesirable, and was shown to be more costlyy than a new and separate high level conduit from the O'Shannassy River. The Murray Government, after conducting a full enquiry, ac- ceded to the new proposition, and the whole of the O'Shannassy watershed of 32,600 acres was vested in the Metropolitan Board of Works for water supply purposes solely in 191o. The permanent survey was commenced in Igio, and the first contract for construction was let in October, 1911. By November, 1912, contracts for practically the whole of the pipe lines and aqueduct, aggregating 49/ miles, had been arranged. The total cost of the scheme is estimated at £450,000. THE O'SHANNASSY RIVER. This important tributary of the Upper Yarra rises in the slopes of Mounts Strickland, Grant, and Arnold, and junctions with the I08. VICTORIAN INSTITUTE OF ENGINEERS:

River Yarra about 8 miles above Warburton. The geological formation is dacite, for the greater part, the balance being shales and sandstones. The rock is covered by a deep and porous humus, and a heavy protective growth of forest and scrub. The result of the preservation of the country in its natural state is a very reliable stream flow and a water of high quality. The low- est recorded gauging extending from the year 1901 has been 20,000,000 gallons per day, and this was taken as the total mea- sure for the capacity of the new conduit. IMPORTANCE TO THE METROPOLIS. The establishment of the new conduit will be of the greatest advantage to the metropolis for all time, for the following rea- sons :- I. It will provide an entirely new and independent source of supply. 2. It will govern by gravitation every possible development of the higher levels of the metropolis. 3. It can deliver water in large volume to both the existing systems of supply without any further expenditure. The result will be a duplicate system of supply to every part of the metropolis. DESCRIPTION OF SCHEME. Capacity, Etc.—The O'Shannassy River will be diverted at a point 3i miles above its confluence with the River Yarra by means of a concrete weir. From this point a conduit of 20,000,000 gallons per day capacity, 494 miles in length, will deliver the water into two service reservoirs at Surrey Hills, the larger of which has a capacity of 15,000,000 gallons, and is part of the new expenditure. The conduit comprises :- 23 miles of open or covered channel. 3 tunnels aggregating in length a little over half a mile. 231 miles of steel pipes, from 34 in. to 36 in. diameter. mile of reinforced concrete pipes 384 in. in diameter. 2 miles of wood stave pipes from 30 in. to 36in. in diameter. i.e., a total of 254 miles of pipe line; 231 miles of channel and tunnel. Location and Elevations Governed.—From the diversion weir on the O'Shannassy River at 98o ft. above sea level the conduit fol- PAPER -NOTES OF THE O'SI-IANNASSV SCHEME. I09

lows the mountain slopes on the Northern side of the River Yarra to a point about 2 miles west of the Don River, Launching Place. at elevation 890 ft. An inverted syphon conveys the water through Killara and Seville to Wandin. Thence the conduit fol- tows a line south of and in fairly close proximity to the Warburton Railway to a point about 2 miles S.E. of Lilydale on the main western ridge of the Olinda Creek. Here a pipe head reservoir of about 11,000,000 gallons and screening chambers are to be constructed at an elevation of 671 feet. The inflow to this reservoir will be measured in an ordinary gauging weir, and a Venturi meter will register the discharge by the main outlet pipe. From Olinda Reservoir the water will be carried 141 miles via Mitcham hill (5ro ft. R.L.) to service reservoirs at Surrey Hills (43oft. R.L.), by means of a 36 in. steel pipe line. The total head thus expended between O'Shannassy River weir and Surrey Hills is 55o ft. The maximum elevations governed from Surrey Hills are :- t° Canterbury, 38o ft. and 320 ft. (isolated small hill tops). Deepdene Hill, Kew, 281 ft. Corner Glenferrie and Cotham Roads, Kew, 236 ft. Malvern Town Hall, 203 ft. Land Acquisition.—The Metropolitan Board of Works has ac- quired the fee simple of all lands, excised from private property by the conduit. The width of the excision is at least 2 chains for open channel, fenced on both sides. For pipe lines one chain in width has been secured under conditions that it shall not be fenced. Service Reservoirs.—In addition to the Pipe Head Reservoir near Olinda Creek already referred to, provision foi- future reservoirs in the highest part of Mitcham has been made by the pur- chase of 321 acres of land. Here it will be possible to provide for storage to the extent of 6o to 70 million gallons. But at the out- set the water will be delivered direct to a new reservoir of r5,000,000 gallons capacity at Surrey Hills, which will be utilised in conjunction with an adjacent 9,000,000 gallons reservoir. The latter has hitherto served the eastern suburbs with water delivered direct from Yan Yean Reservoir, and both reservoirs can so be supplied if it be necessary to temporarily cut off the service by the O'Shannassy pipe line. I I U VICTORIAN INSTITUTE OF ENGINEERS :

Provision for the Future.—Full provision is being now made for the flow from extension aqueducts to Armstrong's Creek and the Upper Yarra, the conduit being constructed in such parts as tunnels, covered way, crossings and basins to treble the present capacity, i.e., to 6o,000,000 gallons per day. The complete future enlargement of the conduit will be effected by simply raising the cement mortar lining in the slopes of the present open channels, and at first duplicating, and then triplicating the syphons. DESIGN AND CONSTRUCTION NOTES. Channel.—The open channel has been constructed to the following dimensions for a 20,000,000 gallons per day discharge :— Width at top, 9 ft. 3 in. Depth, 3 ft. 4z in. Shape.—Quadrant of a circle in invert with I to I slopes. IIlI Inclination.-2 ft. per mile. The discharge has been calculated by means of , Kutter's formula, the value of " n " being taken as .015. The channel is founded everywhere in the solid ground. The lining used is of cement mortar, 3 in. in thickness, and composed of 4 parts of stone toppings to I part of cement, and is trowelled to a smooth and even surface. The specification provides that toppings shall be free from screenings exceeding 4 in. gauge, and shall contain not less than 30 per cent. nor more than 40 per cent. of stone dust. The stone used for toppings has mainly been de- rived from Cave trill Quarry, Lilydale, or from Black's Quarry, Coldstream, though a little bluestone toppings were used from Melbourne. On the Warburton to O'Shannassy River section toppings are being crushed in situ from the local dacite. The use of stone toppings was decided upon because of the almost entire absence of suitable sand in the district, but contractors at all times had the option of using approved sand in proportions of 3 Is sand to I cement, which was about the equivalent in strength of the 4 to I stone toppings. The toppings used have made excellent work. They were con- tinually tested in comparison with sand, and some results of comparative tests are appended. Pipe Lines.—Three classes of material for construction have been adopted, viz., steel riveted or lock bar pipes, reinforced concrete, and wood stave pipes , PAPER-NOTES OF THE O'SHANNASSY SCHEME. I I I

Steel Pipes.—Riveted pipes 4 in. plate with 5-16th in. spigots were used between Surrey Hills and Mitcham. Between Mitcham and the mountain sections of the aqueduct near Woori Yalloc'.c, which length constitutes the main part of the pipe line, lock bar pipes were used, except for 2 syphons in concrete and wood stave. The lock bar pipes were 5/16th in. plate throughout. The minimum thickness of 5/16th in. was adopted mainly out of considerations of strength to withstand caulking at the joints, while at the point of greatest working pressure on the line this thickness was sufficient to provide a factor of safety of 3.75, taking the tensile strength of the steel at 23 tons per square inch. The pipes were laid with the lock bar joints on the horizontal axis in the trench, so that these, the most important parts of the joints, might be in the most advantageous position for caulking. Where branches were required for scours, etc., the lock bars were turned to the vertical axis by means of 4 joggle thimbles, so that saddles might be fixed horizontally on the solid plate parts of the pipe clear of the lock bars. The calculation for discharge of the pipes was based upon a value of n=.o13 in Kutter's formula. The pipes were coated with Trinidad asphaltum and coal tar in proportions of 6o per cent. of the former to 4o per cent. of the latter. The outside coating was reinforced by hessian bound around the pipe after its with- drawal from the coating bath, further coating then being applied thickly with brushes and sand used to harden the surfaces. The plasticity of the coating material was varied to suit weather conditions, the objective being to get as soft a coating as these conditions would admit. The pipes were trucked, 8 on a truck to various stations on the Lilydale and Warburton railway line, and transported to the site for laying one at a time on jinkers. Very little injury was done to coating, and only such as was readily repaired, and it may be claimed that the whole pipe line has gone into place in excellent condition as far as coating is concerned This is a most important consideration in the life of the pipes, which should be very good, the ground passed through being ex- ceptionally favourable, while the internal attack from the water is known to be very light. Wherever pressure conditions were severe in flats liable to flood, or wherever creeks were crossed, the thimble joints were run solid with lead. In places pipes and joints were entirely I12 VICTORIAN INSTITUTE OF ENGINEERS:

surrounded with concrete. In all ordinary cases the thimbles (which have a total width of 8 in.) were run with lead for 22 in. in depth on each side of the thimble. Reinforced Concrete Pipes.—These were constructed in situ in continuous lengths. The walls were 32 in. in thickness of cement mortar, composed of 3 parts of stone toppings to I part of cement. The reinforcing material used was expanded metal rolled to cir- cular sections, and temporarily held in place by wiring. The maximum pressure in any part of these syphons is 3o ft. The internal diameter is 382 in., the value adopted for n in Kutter's formula being n=.o15. The pipes were not rendered, but were brought to fairly smooth faces, on removal of the laggings, and then received a coat of neat cement wash. It was found very advantageous to construct in advance the base plate of concrete 18 in. wide, as shown in type section, as this formed a solid bed on which the pipes could be built. Without this bed the expanded metal was liable to be worked out of place, and press through the soft concrete into the soil. The construction in advance of the bed plate was also found to lend itself advantageously to dealing with water collected in the bottom of the trench. In spite of every precaution cracks occurred transversely between sections of two days' work due to contraction. These leaked when water was introduced, but were repaired satisfactorily and both syphons made perfectly watertight. Experience in this class of continuous pipe line has led the author to the view that in long lengths it is advisable to put a light covering of earth over the pipe as soon as possible after completion, instead of leaving the upper part exposed until completion of testing. Otherwise some form of expansion joints are necessary, but it is desirable to avôid the use of these if possible.

Wood Stave Pipes.—This form of construction being a new one and upon its trial, so far as its use in the Melbourne water system is concerned, localities were selected which were considered particularly favourable for the purpose, viz., inverted syphons in bush country, where leaks in the early stages of filling and testing would cause no damage nor difficulties. The pipes in these larger sizes are constructed in situ of Oregon staves If in. in thickness, and 51 in. in width. The staves are fitted with small tongues and grooves on longitudinal abutting surfaces, and steel tongues are used at the ends of abutting staves. Steel bands 2 in. in dia- PAYER—:NOTES OF T}IE o's -IANNASSY SCHEME. I13

meter are used to take the entire tensile strain due to hydrostatic pressure, being spaced accordingly. The wood serges the purpose of the watertight medium. The pipes leaked considerably when filled with water, but are being made tight successfully by the use of soft wooden wedges driven between the seams where leaks are showing. It is an essential condition to their durability that the pipes be kept constantly full of water, and they have only been used where such conditions are assured. On the question of durability, which is one of the principal factors for consideration in the use of this class of pipe, of coarse nothing can be said at present as far as the Melbourne water system is concerned, but it will be a matter of observation and much interest. Tunnels.—The two principal tunnels are 6 ft. internal diameter, the remaining short tunnel at Evelyn being 7 ft. All tunnels are capable of discharging the full ultimate amount of Q'Shannassy and Upper Yarra diversions, viz.: fio,OOO,goo gallons per day. They are lined with cement concrete, except in sound rock, where the roof will not be lined. Bridges qnd Crossings.—Permanent construction has been em- ployed for the most part. The principal bridge is one of plate girders on concrete piers to carry the pipe line over the River Yarra near Woori Yallock, provision for three lines of pipes being now made. The two principal spans are 65 ft. 6 in., and the bridge is on an incline of I in 15—the result of natural conditions at the site and the desire to lessen vertical changes in direction of the pipes which carry a pressure of 264 lbs. per sq. inch at this point. The crossings and covered way in the open channel sections are almost entirely of flat slab reinforced concrete construction built in place. Culverts.—The principle adopted throughout the work was to carry the flow of all water courses and creeks underneath the channel in concrete or stoneware culverts, and no overhead flumes have been used at all. This method of construction gives special faci- lities for dealing with inflowing water met during channel construction, as well as with the permanent creeks which cross the line. All culverts are made in two grades only, so that from inlet or outlet end rods may be inserted in case of any stoppage. CONCLUSION. The present position of the works is that, with the exception of a few minor breaches and uncompleted details, the whole con-

7 14 VICTORIAN INSTITUTE OF ENGINEERS:

duit is practically completed from Surrey Hills to Warburton. The Olinda Reservoir has not yet been commenced, but there is a 36 in. pipe by-pass around it. On the last Iol miles of conduit between Warburton and the O'Shannassy River weir the work is well advanced, the earthworks being practically completed for over of the length, while the lining of the channel is now being actively proceeded with. One tunnel has been holed through, and the last tunnel has been driven for over of the total length. The contract date of completion is November, 1914. For permission to make the foregoing communication the author is indebted to Mr. Calder E. Oliver, M.C.E., M. Inst. C.E , Engineer-in-Chief of the Melbourne and Metropolitan Board of Works, which controls the water and sewerage services to the city. He also desires to acknowledge the valuable assistance received in carrying out the work from Mr. J. L. Nolan, C.E., who has had charge of the survey and construction works, and from Mr. E. Seitz, C.E., who had charge of the designing work. Table of Comparative Tensile and Compressive Tests for Cement Mortar for O'Shannassy Aqueduct

Breaking Strain average in lbs. per Material. • Cement Age square inch. used. Remarks. â Tensile. Compres'n. Lilydale Limestone j Toppings* S 3 to r K.B. & S. 8 days 233 24026 do. The average o 4 to 1 „ ,, 163 19040 results is base( do. 5 to I 1, , , 93 12880 on at least 3 tensile tests it each case an d generally on t s s Stone toppings from) p r essiox tests Black's quarry ` Coldstream J 3 to i K.B. & S. 8 days 203 19600 do. 4 to i „ 120 15680 Frankston Sand ... 3 to 1 K.B. & S. ,, 120 ó12o These t es t s were taken in conjunction with the previous stone toppings tests Dacite crushed at)j Mann- Warburton 3 to i heimer 8 days 326 do. 3 r t0 I „ ,, 270 do. 4 10 1 „ 236 ?'rankston Saud ... 3 to I „ 123 These test s were taken in conjunction with the dacite toppings tests I.e. 3 parts of Stone Toppings to I part of Cement.

PAPER-NOTES OF THE 'O' SHANNASSY SCHEME. 115

Table of Comparative Tests of Cement Mortar Slabs under Transverse Strain, made at Melbourne University Laboratory.

Break- Breadth of Depth of. Ultimate F -3W Remarks. Description. Span. rnB Deflection 2BD2 Slab. Slab. Load. 1 B D lbs. .inches Lilydale Lime- . The age stone toppings of a 11 * 4 to 1 . 14 in. 6.02 in. 3.05. in. 1300 0,012 487.4 samples 14 in. 6.òoin. 3.0o in. 1400 0013 544.4 tested 14 in. 6.03 in. 3.05 in. 1300 0.017 486.6 w a s 28 Black's stone average 506.1 days. topping Cold- stream 4 to I _ _ 14 in. 5.97 in. 3.00 in.. 1200 0.005 469.0 14 in. 6.00 in. 3.00 in. , 1200 0.005 466.7 14 in. 5.95 in. 3.o3 in. 1210 0.003 465.2 Bluestone top- . average 466.9 pings from qq Melbourne 4 10 I . 14.in:.. 6.00, iu. 3.00 in. $30 0.001 322.8 14 in. 5.98 in. 3.01 in. 85o 0.002 329.4 14 in. , 5.95 in. 3.00 in. 625 0.018 323.6 Bluestone fine . average 325.2 concrete coin- 'posed of 2 parts screenings 4-in., 2 parts top pings, 2 parts sand, i part) cement / 14 in. 6.04 in. 3.03 in. Boo 0.002 303.1 14 in. 6.02 in. . 3.00 in. 785 0.003 304 3 14 in. 6.ç,0 1n. 3.00 it,. 700 0.012 272.2 . average 293.2 Frankston sand to 1 ' ... 14 in. 6.03 '3in..03 in. Boo 0.003 303•5 14. in. 6.03.1n. .3.03ín' 780 " 0:004. 295.9 14 in. 6.02 in. 3.02 in. 725 0.002 277.3 ------average 292.2

* i e.; 4' parts of Toppings to I part of Cement. Reinforced Concrete Siphons-O'Shannassy Scheme : Tests of Density of Lilydale Limestone Toppings, Voids in Lilydale Limestone toppings used for O'Shannassy Aqueduct S 28.o% Voids in 3 parts of same toppings to 1 part sand 28.8% I „ 29.1% sample of sand used ... ••• 39.0% Nom : The sand used was Frankston sand. The tests were made with the view to determining the most dense material possible for use on reinforced concrete siphons. They show that the stone toppings as above gave the best result, without addition of sand, and they were so used in.the work.in proportions 3 of toppings to 1 of cement. I16 VICT0ß4AN INSTITUTE OF ENGINEER S. DISCUSSION. The PRESIDENT said he was sure all would agree that Mr. Ritchie's contribution was a most valuable one—admirable from the points of view, both of matter and manner. He was voicing the general feeling when he said the Institute was deeply indebted to Mr. Ritchie for the trouble he had taken in giving an account of the great work he had in hand. He thought Mr. Ritchie might consider himself fortunate that in his career he should have been associated with such a work as that, which was calculated to be of such benefit to the community. Mr. JAS. ALEX. SMITH had much pleasure in supporting, for the reason, amongst others, that one of his relatives gave, in the early "fifties," Melbourne its first water supply by a pumping in- u!u stallation supplied from the Yarra, close to Flinders-street. An- other of his relatives—the late Councillor A. K. Smith, M.L.A.- had as an engineer, as Mayor of Melbourne, and from his place in the House consistently advocated the reservation in perpetuity of the virgin country of the Upper Yarra for the City's future needs.

i IGI Later, had Mr. Wm. Davidson not strenuously opposed, the land would have been alienated by past Governments for settle- ment, and the opportunity would have been gone for all time. It was a matter of which they might be proud that all the great works which Mr. Ritchie had described, and those which he had referred to, and with which he had been intimately associated, had been under the control of two of their own Past Presidents, the late Mr. Wm. Thwaites and Mr. C. E. Oliver, the past and present Engineers-in-Chief to the Metropolitan Board. The PRESIDENT suggested that before he called on Mr. Ritchie to acknowledge the expression of appreciation, opportunity should be taken by the members to propound any questions which occurred to them before they had an opportunity of reading the paper. He was sure Mr. Ritchie would be very glad to enlarge upon any points that had created a difficulty in the minds of members, or upon which they desired further information. Mr. J. A. SMITH asked what timber Mr. Ritchie used in the wood stave pipes? The PRESIDENT said he had made but a very few notes. He had found himself t.Do much absorbed in listening to Mr. Ritchie and DISCUSSION—NOTES OF THE o'SH4NNASSY SCHEME. I17 admiring the lantern views to take up a critical attitude. The designers of the scheme had been extremely conservative in the matter of the co-effc:ents of rugosity and the capacities of the various conduits, and in view of the fact that such a great amount of care was taken with the lining the co-efficient .015 seemed extremely conservative. But he would suggest that there seemed to be an excellent opportunity, before the lining of the channel became affected by cracks or incrustations, of testing on a large scale the correctness of the co-efficients. He would be interested to hear whether Mr. Ritchie had had an opportunity of measuring the discharges, and thereby deducing confirmation or otherwise of the co-efficients which Kutter gave. All their lives they had based every hydraulic calculation on Butter's co-effcients, and it would be well to know from a high authority like Mr. Ritchie if he had in practice secured the confirmation of those co-efficients. Then again, it occurred to him that they had seen many in- stances in concrete conduits of cracking at the joints through thermal movement, and he would like to know if Mr. Ritchie had had trouble in that direction. In the Sydney water supply a very considerable amount of damage had been done to the main conduit by expansion and contraction. It would be interesting to be told what Mr. Ritchie's experience had been in that regard. He did not know whether he had heard correctly that the Sur- rey Hills Reservoir had a capacity of only 15,000,000 gallons. In view of the fact that the daily discharge capacity was 2o,000,000 gallons, he would like to know the reason why the Surrey Hills Reservoir was not of much larger capacity, say two or three days' supply, to provide for the main supply being cut off for repairs to the main conduits. These were just a few questions to give Mr. Ritchie an opportunity of engaging their attention for a little longer. Mr J. S. I)ETHRIDCE said the President had anticipated some of the points he intended making in respect to the excellent opportunity of checking the co-efficient of contraction. Before going any further he would like to endorse the remarks of the previous speakers as to the pleasure he had had in listening to Mr. Ritchie's excellent paper. Everything in connection with the water supply brought up pleasant memories. They had never had any really bad trouble. The country through which the scheme passed was some of the most beautiful in Victoria, and those who had visited it had pleasant remembrances of it. 118 VICTORIAN INSTITUTE OF ENGINEERS : The President having anticipated some of his remarks, he would like to also remark on the excellent opportunities there would be for testing the durability of the many kinds of materials involved. He did not suppose there had been any work carried out recently which would throw so much light on many points in respect to which questions were raised by hydraulic engineers. To begin with they had the mild steel pipe and the locking bar pipe. They knew of an immense scheme carried out in Western Australia with those pipes, and there had been considerable trouble experienced from pitting and corrosion. He had no doubt the extreme care taken with the coating in the case of the pipes used in the O'Shan- nassy scheme, and in view of the considerable experience the Me- tropolitan Board had had with that class of pipe, had given them the assurance that they could not go far wrong, but he was sure that pipe line would be watched with very great interest. The wood stave pipe, too, would be watched with much interest, be- p;1 cause some 20 years ago the Victorian Water Supply Department, in carrying out a scheme, constructed an immense oregon flume 120 ft. wide in the bed and several chains long. The flume was 01111 in a different position to the wood stave pipe used by Mr. Ritchie, but the Oregon was rotten in five years. He knew the Water Supply Commission was laying oregon pipes with satisfactory results, and there was abundant evidence to the effect that under proper conditions good results could be got from them. Then they came to the reinforced concrete syphons. There they had a material not so much open to question. But he would like to ask if, in arranging the reinforcement, any special provision was made for taking up the longitudinal tension stresses. He had seen some very considerable work of that sort carried out, ranging in diameter from 3 ft. bin. and nearly 8o ft. head. That, he thought, was a great deal higher than anything in connection with the present scheme. The reinforcement was of expanded metal, and the longitudinal reinforcement was just common round bars, and that was very successful. Another point that struck him was as to how the centre was taken out of the pipe after it was finished. He would like to know how it was done. Mr. J. A. Smith had referred to the historical aspect. That week he had been looking through some papers, and picked up a 4 printed report of the Parliamentary inquiry of 1852 into the Mel- DISCUSSION-NOTES OF THE O'SHANNASSY SCHEME. II9 bourne water supply. The authorities at that time seemed to favour a scheme of supply from the Yarra from Dight's Falls, and pumping it to a tank at Studley Park. But at that time they were raising a question as to whether pipes were wanted, so he thought they had progressed somewhat in having adopted the scheme outlined by Mr. Ritchie. Mr. M. E. KERNOT said he would like to express his appreciation of Mr. Ritchie's paper. He had given them much to think about, but had not introduced any contentious matter ; so he would rather praise than criticise at present. One would like to be assured as to the safety of that water supply, and that all precautions had been taken to prevent the land- slips coming down in the future, for as far as his experience went if there were any troubles of that nature there they would have big slips coming down which would smother the aqueduct. As to the wood stave pipes, the thought struck him, how did Mr. Ritchie protect the steel bands placed outside them? Especi- ally in the places where there was a good deal of it. That could hardly be guarded so carefully as the locking bar pipes, and if there was any acid in the soil and the steel strapping gave way, they would have trouble in that direction. He had no doubt Mr. Ritchie had a complete answer to the question. Mr. J. H. D. BREARLEY congratulated Mr. Ritchie on the interesting lecture he had given; and on the excellent lantern slides. He wished to ask by what method the work was carried out. Was all the work done by contract, or was any portion carried out by day labour? Also, as to whether any further appliances than scoops and ploughs were used. He had much appreciated Mr. Ritchie's remarks about wood stave pipes, and as to getting very high heads, because the wood stave pipe became a very expensive matter when it had to be strapped every few inches. One of the claims of the pipe was its cheapness. It seemed to him rather curious that in a permanent work of that description and of such magnitude an experiment of that sort was justifiable for an inverted syphon. He would like to hear a few more remarks from Mr. Ritchie as to what led up to the use of the wood stave pipes under those particu- lar conditions. Mr. Ritchie had referred to the fact that a Io ft. roadway was available all along the aqueduct. He was very pleased to hear I 2o VIC'l'o(t1ÀN líl.'ST11'UIe OF Et3GINEEIS;

that, and hoped the Board would give them an opportunity of traversing it. The PRESIDENT invited Mr. Ritchie to address himself, if he wished to do so, to the questions that had been put that evening, pending the fuller discussion at a later date. Mr. RITCHIE said with regard to the questions which had been raised, Mr. Smith had been answered by Mr. Dethridge. The timber in the wood stave pipes was oregon, kiln dried, and of high quality. The President had asked some questions regarding the coeffi- cients of discharge, and the value used in their calculations. That gave him an opportunity of explaining. It was quite natural that such a question should arise. The co-efficients had been based on experience in their existing conduits. They had taken careful measurements, and found the co-efficient they had used was not too h;gh. There were times when the growth of algae on the sides of the channels affected the flow so much that they had got as much as .016. By actual measurement they had come to the conclusion that .015 was a safe co-efficient to work upon. The same thing applied to their pipe lines. They knew their co-efficients seemed rather high for those pipes; but they had based them on the results of observed flow in their mains as well as in their aqueducts. Regarding expansion and contraction in long lengths, the Pre- *Went had asked if much damage had been done. They had had very little trouble, because they adopted the precaution of filling the channel with water on the completion of every 1,700 feet of length. As a result the channel never remained long without being filled . The channel, as seen to-day, was in a remarkably- good condition in that respect. Regarding the President's further question as to the capacity of the Surrey Hills Reservoir being only 15,000,000 gallons, that again was a natural question. But they would remember that he had called attention to the fact that there were 9,000,000 gallons reserved on the other side of the road. The two in conjunction would give a storage of 24,000,000 gallons at that point. Had the conditions existed at the site they would gladly have built a much larger reservoir there, but the extent of ground available for constructing reservoirs at that point was very limited, and they did the best they could with the conditions at the site. DISCUSSION-NOTES OF THE O'SHANNASSY SCHEME. 12

Mr. Dethridge had referred to an experience in Western Aus- tralia as to pitting and corrosion in pipes used there. There was a greater length of locking bar pipes in use there than there was here, and all the information he could gather pointed to the conclusion that the trouble there had not been one of the fabrication of the pipe itself, but it had been with the coating. From all he could learn the pipes were lying exposed to various conditions of weather for twelve months, and in some cases longer. Thus the heat caused the coating to run on the inside, and the outer coating Was destroyed to a great extent. Further than that, the water there was very bad compared with that of Victoria. In putting the pipes in position they had the experience of Western Australia in mind, and were ,fully seized of the fact that the life of the pipe might in a sense be said to be the life of the coating. The strict- est instructions had been enforced regarding the handling and putting in place of the pipes. If men had to go into the pipes they had been Compelled to take their boots off, or wear rubber shoes. Moreover, they had used solid run joints in special cases They had adopted a form of bandage on the outside made of canvas, and then the thimble joint was run from the outside. There were other causes why the Coolgardie pipe gave a great deal of trouble. They were partly laid on the surface, and the method of jointing meant the operation of a lot of men inside the pipe. His experience had led him to keep the men outside the pipe. Their most experienced jointers, who knew the value of the coating, were the most careless ; they found the only thing was to keep the men out of the pipes by all possible means. An- other thing was to get the pipes into the ground as soon as possible, and their aim had been to have a gang sufficiently strong to lay the pipes as soon as they were delivered. Where the pipes Were exposed the bitumen suffered through exposure to the Weather, and became friable, and so that point was kept very closely in view. Mr. Dethridge had referred to the oregon flumes. They rea- lised that wood stave pipes should only be used under conditions where the wood was constantly under the influence of water. In the inverted syphons, where the flow would be intermittent, they had used iron pipes down to the level, in order to get the condition of constant filling with Water for the wood stave pipes. Of course, as Mr. Dethridge had said, they would have to watch developments of those pipes. He might also refer to Mr. Brearley's remark 122 VICTORIAN INSTITUTE OF ENGINEERS. as to whether it was justifiable to use pipes of that description. He might say it was desirable to test any new form of construction under as wide conditions as possible. It was desirable, in the interests of general economy, to use as many different kinds of construction as possible, and public bodies should have some faith and some en- terprise in adopting such different kinds of construction providing they worked within a reasonable limit. He did not think the Metropolitan Board had made any leap in the dark in going the extent it had done. Some two miles only out of 25 of that class of construction had been adopted. They had conditions which were particularly favourable. They were in the middle of paddocks where there was no trouble through leaks likely to arise. But it was a very favourable place for such an experiment ; and if the wood pipe was all that the wood pipe company claimed for it, it would be a considerable help in engineering works. Of course it had been a good deal cheaper. They has adopted it not only on the ground of a new form of construction, but because of its economy. They had called competitive tenders for the whole work under different sections. They had wood pipe tenders and steel pipe tenders, and estimates for reinforced concrete for parts of the work as well. Of course the main competition, as far as the contractors were concerned, was between wood pipes and steel pipes, and they had chosen those which were most advantageous to the Board from the point of view of economy, etc. With regard to reinforced concrete, and as to whether any provision was made for longitudinal movement, there was no provision made for expansion joints. The movement which took place was mostly in the upper part and not extensive. With reference to removing the centreing, no difficulty was experienced in that. Probably the photo. hardly showed the detail of the wedge adjustment. As to the safety of the aqueduct, and the possibility of slips in the future, there was the possibility of slips which might damage the aqueduct; but they had followed the principle that if they were able to find any indications of slipping they had gone back into the solid ground, and they had every reason to believe that no slip would take place for more than five or six feet from the surface. Wherev4er they had seen anything worse than that they had benched it. But he thought that during the first two years of construction,

DISCUSSION-NOTES OF THE O'SHANNASSY SCHEME. I23

during which they would have the work under observation, they would have had the greatest danger from slipping. In that country the growth of timber was very strong, and soon the surface would become covered again, and in two years' time would be in a much better condition, and less liable to slip. The Government had been wise and good enough to give them protective strips on the upper side to protect them against denudation of timber and resultant slips close to the aqueduct. Regarding the other question by Mr. Kernot as to the steel outside the pipes and how it was protected, that was a point which had troubled him, because the coating which was used for that class of construction required to be modified. When he first saw it carried out they used the asphaltum coating, but he was not long in coming to the conclusion that it would not do at all, because the band had to be got into place, and the coating was injured in the process. So the form of coating they adopted was coal tar. The bands were treated and dipped in coal tar. That form of coating was very serviceable, and stood a great deal of knocking about, and he had reason to think that if the wood pipes had as good a life as their experience led them to expect for the bands, the wood pipes would give them very great satisfaction indeed. He might say that in considering the different classes of construction of wood and steel, they had worked out the comparative costs, not only on a question of first cost, but of interest and re- newals, and they estimated that, assuming a certain life for the wood pipes they could afford to replace them in a certain number of years. But he could not say how long the wood pipes would last. They had to find that out. There was a diversity of opinion as to what the life of the wood pipes would be, and they were endeavouring to find that out under their own conditions. In reply to Mr. Brearley's reference to the slides, he,would like. to say the photographs were taken by one of the members of his staff, Mr. H. A. Wood, and they were a credit to him. He was glad the slides had been appreciated. Regarding Mr. Brearley's question as to how the work was carried out, whether by contract or by day labour, he was not able to say exactly what was the policy of the Board at all times. but as far as he had been able to observe the general consensus of opinion was in favour of carrying out the work by contract, and eliminating day labour. That principle certainly had been fol- I24. VICTORIAN INSTITUTE OF ENGINEERS:

lowed in the present work. All the aqueducts and reservoirs were carried out by contract, also the manufacture of pipes and the manufacture and laying of wood stave pipes. But the excava- tion for the wood stave pipes was done by day labour. The practice of the Board was to train up its own skilled jointers for jointing that class of pipes, and therefore it was generally more advari- tageous to carry out that work by day labour. As to labour-saving appliances, nothing further than ploughs and scoops had been used. With regard to Mr. Brearley's reference to the ro ft. roadway, he hoped it would be used by members of the Institute. They would be glad to see members while the work was in course of construction, and after it was finished he thought for many years '1011 V to come it would be a site for inspection, both as to the engineering work and the scenery. Discussion adjourned. Plate I. MELBOURNE WATER SUPPLY, ú ROWING YAN MEAN, MAROONDAH, AND O'SHANNASSY SYSTEMS.

SCALE

.ne, e e . , e a • A

M`Grant sappoinanont

T olangi ez !Ftey, Narbethonn Ma- RA F. Whiktlesea E RIVER

W: ERSH D

x ì. TA Van Sean s2,6+0 c YARRq

A QUEDUC Queenstown OSES S'" Han Sean

Noma Hal Healnun.Ile. MARRA WAT RSNED Bursts Bridge Grandanic M'Iloons Conpaai S' ACRES(Approx.) S'- Morangé • k 1R°Ang oTq Epping I' Pp. HEAD xznge Boo NF.SEev1a1N 'Horst's]] and Geek ri Warburton Gre nsborough Receardi Millgrore ~. Eltham Warburton West

L"lHnale Woori•YalloCN Mara./ notino NORTE , N'ne5DON, • Esc, yn Mooruo/hash Jvdo rallegro Croydon NA; .taN

ingwood Kn J.t hFr p Rays.1 er -- Th Beenak ~0°a

ÿu

• OTT! NG UIILL born brook Emerald •,` iji POET PIEILLIP

'ordlanuL Plate 11. M,M.B.W. O'SHANNASSY SCHEME. GENERAL TYPE SECTIONS.

FENCE

GENERAL SCALE FEEL 0 6 12 2D FEET pl~ SCALE of DETAILS INCHES 0 i < .t s p 70 INCHES SDE

— Channel — — Reinforced Concrete Pipe —

RDA RIM Y Not /ess than /O Met Korde

.r Cement Mortar

— Lock Bar Pipe —

unto STEEL %tc'

OPEN CLOSED

/ Detail _— Tunnels —

Through Rock Wood Stave Pipe —

ó/> t.ourete

Renderr n 74. BL;Concrete WLOIW 5,4' 00trr 'Cement ///ameter Rendvr.,

Oregon stares /ffs't re.4. v_ lp oeo7 o ain r«b,Kor r O a n Steel Bands % diameter: (1Jetatl

Plate I V.

OPEN CHANNEL NEAR WARBURTON.

SETTLING BASIN IN OPEN CHANNEL.

Plate V.

SETTLING BASIN ON CUR V E.

OUTLET BASIN TO INVERTED SYPHON l Plate VI.

INCIPIENT SLIP, SHOWING BREAK IN LINING OF OPEN CHANNEL.

LAND SLIP IN CHANNEL. / Plate VII.

FIXED AND PORTABLE MIXING BOARDS FOR CEMENT MORTAR 4,:

PORTABLE MIXING BOARD DISCHARGIN(.

Prate VII!.

PORTABLE MIXING BOARD AFTER DISCHARGE.

30 IN. WOOD STAVE PIPE. I Plate IX

30 IN. WOOD STAVE PIPE.

30 IN. WOOD STAVE PIPE CROSSING CREEK. J Plate X.

382 IN. DIAM. REINFORCED CONCRETE SYPHON NEAR EVELYN.

REINFORCED CONCRETE SYPHON 382 IN. DIA. CROSSING DEE RIVER. _ DISCUSSION : THE O'SHANNASSY RIVER WATER SCHEME. 155

DISCUSSIONS.

THE O'SHANNASSY RIVER WATER SCHEME.

Mr. J. T. N. ANDERSON forwarded the following notes :— This is one of the most valuable papers recently read before the Institute. Such contributions form the real assets of our Society, and the opportunities which we afford our fellows to become fami- liar with our works while they are in hand and coming into being constitute a feature which is, perhaps, the most valuable of all the benefits which our membership affords. It has been suggested that Mr. Ritchie may later on make experiments to determine the co-efficient of rugosity in his materials, viz., steel, concrete, and wood. It is greatly to be hoped that he may. The writer considers that the co-efficients used by the Board err in being a good deal too conservative. In this, however, the Board errs in good company, its co-efficients being but little higher than those used by Midgley Taylor and Richard Parsons. The late William Thwaites, however, confessed that had he to re-design the sewerage system of Melbourne, he would not have used quite so high a co-efficient, and, in consequence, the gradients of the sewers could have been flatter, a circumstance which would have saved several hundreds of thousands of pounds in the whole scheme. This matter of checking the co-efficient of rugosity in such a formula as Kutters', is a decidedly difficult, and tedious matter. During the last six months of his tenure of office as Engineer-in- Chief of the Dunedin Drainage Works, and when the large Diesel pumps were in full working order, giving a means of drawing off as much sewerage as could be admitted at any desired velocity up to the maximum obtainable with the grades, the writer made frequent tests, of velocities both "surface" and "average," and, with rolling balls of heavy wood, velocity also at the invert, and the result was that for reinforced _ concrete pipes the co-efficient .012 was proved to be ample, while most results agreed with about .oil. On account, however, of disturbing factors such as growths and deposits, he would in future continue to follow his original practice of allowing for both steel (asphaltum) and concrete surfaces the .013 co-efficient same as Mr. Midgley Taylor. 156 VICTORIAN INSTITUTE OF ENGINEERS :

One other matter. It will be interesting to learn something in future from the experience of the Metropolitan Board—on the question of the relative life of concrete, steel, and wood for pipes. For sewerage work the writer preferred wood stave pipes to steel, but he took care to use red ironbark timber, specially picked and carefully worked into staves 4 in. X 2 in., pitched internally and wrapped externally, with a rubberoid clothing, and for his steel he used well pickled, mild steel, in. round, with C.I. clips. This cost about half what mild steel or C.I. pipes would have. He is convinced that everything depends on the quality of the timber. In his youth in the homeland he has seen elm pipes taken up, and replaced by cast iron in a domestic scheme. The elm pipes had been in use for about 1'13 years. It may not be generally known that the original water supply of London was through such pipes, and they were not all replaced until some seventy years ago. In other words, for over 200 years London was supplied with water under pressure through wooden pipes, and that before the habit of protecting with pitch asphaltum or tar had come into vogue. Also, without iron straps or binding of any kind other than the cohesion of the timber, which was used as it came from nature in the hollow log, the joints being made by tapering a conical spiggot on one end, and on the other end a conical enlargement of the bore to receive the spigot of the next pipe. The chief reason for the rejection of such pipes was their clum- siness, and liability to leak, not that they had a shorter life than the cast iron pipes which replaced them.. Then, again, as a further illustration of the proverb that there is no new thing under the sun, may be cited the ancient prototype of the modern reinforced concrete pipe, namely, the Roman cement aqueduct. Of course this could not be used as reinforced concrete is, under pressure. The pressure mains were in ancient Rome of sheet lead soldered by a longitudinal joint, so as to make cylindrical pipes. In fact, it would appear that the materials which are most modern, and most on their trial for endurance, are in reality our old friends iron and steel. At the same time it is obvious to anyone who has taken an historical interest in the subject that it is a complete innovation to use the more perishable soft woods for so important a service as the water supply to a large city, and certainly in this, as in so many of their strange DISCUSSION : THE O'SHANNASSY RIVER WATER SCHEME. 157 ways, our American cousins would be regarded by their engineering ancestors in ancient Rome or modern Britain as little short of lunatics. The writer understands that the Australian com- panies, who control the manufacture of so much of the wooden pipes here, are experimenting with our Australian hardwoods. He has himself recommended for the purpose certain classes of Mess- mate, which, he is informed, are being used with advantage. It will be valuable to watch this development, because, judging from their performance in other directions, the more durable eucalypts should be the timber for wood pipes, par excellence. The PRESIDENT said it was very interesting to notice the enter- prise of the Metropolitan Board of Works, and its engineering staff in undertaking experiments in such a large construction. On the respective merits of the different pipes he had little to say, except in regard to the wood stave pipe, and there his difficulty had always been the life of the enveloping hoops, because in the end that hoop had to carry the whole of the stress. The wood staves were merely the envelope to contain the water, and did not contribute the resistance to the tension set up by internal pressure. They were required to be substantially identical in quantity with the riveted, or solid, or bar-lock steel pipe, or as much as the reinforcement in the concrete pipe. That being so, they had in the wood stave pipe the anomaly of the vital part of the construction being comparatively the least protected, because, although it professed to be covered with material preventing oxidation, it was put on the most dangerous part of the environment, where there was every opportunity for contact with the protecting medium, for the lodgment of water and so on, so that what would happen in the course of years when the agents of disintegration had attacked the hoops one could hardly foresee. It was risky to place permanent reliance on a local means of preventing oxidisation. It was quite a different matter when the steel was encased in a concrete mass, because the atmospheric conditions which affected the concrete were well known, and cement concrete was a material the durability of which engineers might have confidence in, as they could not have in the more modern materials comparatively untried. They could look for interesting and valuable information from this experimental construction on the part of the Board. 158 VICTORIAN INSTITUTE OF ENGINEERS

Mr. A. S. PAPPRILL (a visitor from Queensland) said he wished to convey fraternal greetings from the Queensland Institute of Engineers. He had listened with profound interest to the paper which had been read. He might state with regard to Australian hardwoods they had recently had an illustration in the matter of longevity of hardwood in piles. One pile recently removed from a structure was of spotted gum, and the record was something like 76 years. The pile was in an absolutely sound condition. The question of Australian hardwoods for pipe line construction was one of great interest. Unfortunately, their Institute in Queensland was yet an infant, but they were interested in a minia- ture way in Victorian research work. They followed it with keen interest, and he hoped to have the pleasure of taking back with him some copies of the papers read before this Institute. Mr. J. A. SMITH asked if they could take it that the discussion would be exhausted at that meeting. It would almost seem a pity if the discussion of such an important subject should be closed if there were other members who wished to contribute. The PRESIDENT said that would depend on Mr. Ritchie's con- venience. Mr. E. G. RITCHIE said he would leave the matter entirely in the hands of the meeting. The PRESIDENT said it was not usual to adjourn a discussion twice. He thought it would be most expedient to close the discussion, as it had already been adjourned previously, and other important business might intervene. Mr. E. G. RITCHIE, in reply, said he had listened with interest to Mr. J. T. N. Anderson's remarks on the paper, and was glad to hear that Mr. Anderson's experiments and experience led to a result of n=.0i3 in Kutter's formula, which coincided, as to pipes, with his own experience. As to the co-efficient .015 in the aqueduct, he thought engineers generally would be inclined to question it as being too conservative. He might explain that it was only adopted after careful capacity measurements, and he did not want it to be supposed that it was because of the degree of fineness which had been wrought out in the lining of the channels, but it was entirely due to the growth of algae in the channels. He might be asked why they did not clean the channels out at more frequent intervals. He found it was not advantageous to clean them DISCUSSION : THE O'SHANNASSY RIVER WATER SCHEME. 159 frequently. The best result was obtained by letting the algae reach the stage of ripeness, and break away of itself, or at a certain stage to send the sweepers through the channel by means of pressure. At certain periods they found the channel did not discharge anything like the quantity it discharged at other times. Therefore the designers thought it advisable to design for the worst possible conditions, realising that they were erring on the safe side, seeing that the channel had to be enlarged by raising the sides. The future was thus left for further investigations. His own view was that, with the higher velocities, they would not be troubled with growth of algae to the same extent as in other channels, because the lodgment would not be so troublesome with water at the higher velocity of the O'Shannassy channel. They would have to find that out in the course of experience, and they would have a good opportunity of doing so, because they would have a measuring weir at one end of the pipe head reservoir, and at the other end a Venturi meter. It was difficult to get capacity measurements which were not influenced by the requirements of consumption, and it was only as they could get a number of reservoirs, so that they could sectionalise the systems for the time being, that they were able to carry those tests out. It was their inten- tion to extend their observations in that respect, and, if they obtained information of value, he would be pleased to place it in the hands of members. As to the use of Australian timber, he understood experiments had been made, but as far as his knowledge went they had not been carried out to any great extent. The reason why Oregon was used was the fact that that wood swells considerably when wet. Whether Australian hardwood would swell to make a watertight pipe was a matter he was not able to speak definitely on. It would be an advantage if the Australian hardwoods could be used. P s to the use of hardwood staves for comparatively low pres- sures, such as sewerage, he should think the hardwood staves might be used under those conditions. But he was not sure whether they could be used where there was a high pressure. With reference to the President's remarks as to wood pipes, it must be admitted that the work, was experimental, and the Board recognised it as such. But as he explained in the paper, the Board was actuated by a question of policy, and desired to experi- I60 VICTORIAN INSTITUTE OF ENGINEERS: li ment with as many kinds of construction as possible. Their experiments were not on a very large scale relatively to the length of pipe line constructed, viz., about two miles out of twenty-five. The life of the pipe was undoubtedly dependent on the enveloping hoops, and if members had anything to do with that class of construction he would like to warn them particularly as to the danger those hoops were subjected to in the course of construction. The machine-made pipe, in which the hoops were protected with coat- 4 ing and wrapped with hessian, were very much less liable to danger in that respect than the pipe they had adopted, because that was a pipe made in a trench, and if there was rock about the coating was apt to be damaged, and when new coating was applied to cold material, in place, with äll the associations of wet and mud, it was not nearly so satisfactory, so that undoubtedly the point raised by the President was an important one. But he would repeat that if the wood would last in those pipes as long as they had reason to believe the steel would last, they would be well satisfied, because they had calculated the three classes of construction on an estimate of annual charges based on the life they thought should be al- lowed for each, and in this respect, later on, they might be able to take a more liberal view than they had done. He did not think there was anything else to reply to, and thanked members for their criticism. The PRESIDENT declared the discussion closed.

FIRE PREVEN'TION AND EXTINCTION.

Mr. J. A. SMITH said he had put one question to Mr. Wilkins at the previous meeting, and he would like to recapitulate. In connection with the City of Melbourne building regulations, the question of fire protection was considered in conferences extending over four years. The committee very thoroughly dealt with fire protection, fire prevention, and fire resisting buildings. It was with the knowledge of what had been suggested as necessary, and what those building regulations would provide for if they came into operation, that he had framed the question that he had put to Mr. Wilkins. It was this :—What was his opinion, from the fire- fighter's point of view, upon the construction of buildings six or eight, or more, $tories in height, without any attempt to render

Library Digitised Collections

Author/s: Ritchie, Edgar Gowar

Title: Some notes descriptive of the O'Shannassy Scheme to supplement the Melbourne Water Supply (Paper & Discussion)

Date: 1914

Persistent Link: http://hdl.handle.net/11343/24570

File Description: Some notes descriptive of the O'Shannassy Scheme to supplement the Melbourne Water Supply (Paper & Discussion)