REPORT ON THE DRAINAGE OF THE CITY OF CHRISTCHURCH.

Lyttelton Times, Volume XXII, Issue 1265, 19 July 1864, Page 4

REPORT ON THE DRAINAGE OF THE CITY OF CHRISTCHURCH.

Th® following is the report of the City Surveyor referred to in our report of the City Council. City Council Office, .Christehurch, July 11th, 1864. (_; -jnxKMF.N, I beg to lay before you the accompanying Report on the Drainage of the City. Preliminary Remarks. C'.avsb 1.— I The City of Christehurch is situate on the >ld delta of the River Waimakariri, and is dirked into two parts by the Avon River, which may be called the North and South. It stands upon an alluvial plain, sloping from the north-west to the south-east. The north portion averages 14 feet and the «outh 12 feet above high-water mark. Th® surface of the town was originally intersected and corroded over its whole extent by the channels of the flood waters of the river and other watercourses, and the site of the town in its natural state has discharged its surface waters both into the Avon and Heathcote Rivers. The rapid occupation of the sections and the formation of the streets have combined to interfere with the original channels and the gullies, which heretofore acted as main drains, have been necessarily dammed up so as to prevent the discharge of the waters which found their way through them. In framing this report I have been guided by the following considerations - Ist. The necessarily intimate connection of a thorough and abundant water supply with sewerage. 2nd. The very large sum of money that would be required to carry out any system effectually combining the two. 3rd. The* very limited powers of the Council to raise money, which I think could only be done by debentures, protected and signed by the General Government as guaranteed. 4th. The vast amount of work to be done in the city which is indispensable, the cost of which will far exceed the rates about to be levied. sth. The conviction that many years must elapse before the Council will be in a position to undertake the necessary works for the accomplishing effectually the above objects, it would therefore be obviously useless to recommend them at the present time. Outfall Drainage. Clause 2.—The annexed Plan, marked B, gives the levels of the intersections of all the streets within the city to a datum of high-water mark, from which it will be seen that though difficult it is not impossible to construct sewerage fromaportion of the city, yet the drainage of a large surface must still fall into the River Avon. The general level of the city is so slight above high-water mark that the requisite fall can only be obtained by carrying the drainage to Christchurch quay, and draining on the ebb tide. The distance to the estuary is so great that I am of opinion it could not be thought of; it would require a covered drain a further distance of nearly two miles, the greater portion of which would be at a dead level, requiring an abundant supply of water for the purpose of flashing, &c. In no case could I recommend the drainage of solid matters to be disposed of by sewerage, either into the Avon or Heathcote Rivers; in the latter I do not think it would ever leave the river; in the former it would be deposited in the mud flats in the estuary.. I would therefore recommend the disposal of the various drainage matters, as will be presently shown in detail. For the north part of the city, the greater portion of which has its drainage by Free's Creek to the Avon, and that portion of the south part ("coloured red on the plan H) laying to the north of the following line, which is the water shed of the south part; viz., from the east belt westward along Hereford street to Colombo street, following the latter to Lichfield street, and thence in a south-westerly direction to the south belt, the Avon River would be the outfall.

The remaining portion of the town south of this line would be carried away by the Ferry Eoad drain. I do not consider that the line of this drain is the best that could be obtained, but would prefer one, if the ground were available, running from the south belt, in aconverging direction, to the present drain, having its outfall at the same place at the Christchurch quay. With regard to the Avon River being made available for the outfall, as before mentioned, I can see no objection to its being used for that purpose ; for it must be remembered that, where flowing through the city and for a considerable distance below it, it is not a tidal river, but a flowing stream, which would carry away the flood waters and liquid drainage without being the least offensive or detrimental to the health of the inhabitants. Section marked A shows the levels of the Ferry-road drain, the gradient of which should be reduced to that shown and converted into a covered drain.

Having thus disposed of the outfalls, I proceed to consider the best means of providing for the drainage within the city. Flood and Surface Waters. Ctause 3.—The disposal of these waters must be by means of the side channels of the streets, and no time should be lost in having thefootways kerbedand the channels properly paved. Disposal op House Slops and Refuse. Clause 4.—This is one of the most important subjects in connection with the drainage of the city, and the following plan appears to me to be the most efficient and economical that can at present be adopted. That under the outside of and clear of the ride drains on each side of the street vitrified pipes belaid; that in the yard or other convenient place of each house there should be a sink with double grating and proper stench trap, which should lead into the pipes already mentioned; the whole of the house slops being thrown upon these gratings, they will find their way into the main pipes, thus only fluids would have to pass through them. The other refuse matters should be thrown into ashpits, with which every house should be provided, and which should be emptied at regular stated intervals. By means of the borings which are being carried out over the city, a supply of water would be available for flushing the drain pipes. At first these pipe drains would have the same outfalls as the side drains near which they run, and as soon as funds are at the disposal of the Council, a dam should be constructed across the Avon River just above the Hospital, retaining the water three feet higher than its ordinary level, for the purpose of flushing a sewer constructed diagonally through the south portion of the town, from the point marked A on the plan B, and in the same direction as shewn by the red dotted line, on the completion of which it would, with some alterations in the levels of the vitrified pipes, so as to lead them into the sewer, carry off the whole of the refuse liquid drainage into the Avon below the city, except a small portion, which would be conducted into the Ferry Road drain. In a similar way the north portion of the town, the dam being constructed at the point C, and following along the dotted line to its junction with Free's Creek, in Peterborough Street. This should then be converted into a covered drain, and its outfall into the Avon diverted to the point marked E. Previous to the vitrified pipes being laid, I do not see any other feasible way of disposing of the house liquid drainage other than their being thrown into the side channels as soon as paved before a stated time in the morning, having a constant stream of water running through them, the channels being kept daily swept by the city scavenger. Disposal of Night Soil. Clause s.—The system now generally adopted for the construction of closets and the use of pans is the best that can be devised. It would be an improvement if a box with some small ashes were kept in the closet, and a small quantity put in the pan each time that it is used; when the duplicate pans arrive, another reserve should be obtained somewhere on the banks of and down the Avon, that the full pans, with their lids on, -being placed in barges, should be floated down the same and thoroughly cleansed. The Drainage of Rural Lands through the City. Clause 6. —It appears not out of place here to refer to the drainage of rural lands into and through the city. At the present time there is a large bulk of water thrown upon the town, and which the council have to provide drainage for, and I consider it imperative that the 63rd clause of the City Council Ordinance should be most strictly adhered to in all cases.

The Open Ditch Drains in the City. Clause 7.—There are at present within the city many open ditch drains, the water flowing through them rising from springs and other natural sources, which renders their existence indispensable; they are situated principally in the least populous parts of the city. They will eventually have to be made covered drains; one of the most important of these ia the south drain running from Section 117, Town Reserves, 200 links from the north side of the South Town Belt, and parallel to it, having its out-

fall in the Ferry Road drain. This drain should be deepened to meet the proposed alteration in the outfull down the Ferry Road. It is the drainages of the South Town Reserves west, of the junction of Madras Street, the Ferry Road, and south of Lichfield Street, and will require to be tnude a covered drain. It would occupy too much space were I to refer to each particular drain of this nature in the city ; and this being a General Report, it would be unnecessary to enter into the whole of the minor details. I luvve endeavoured to bring under the notice of the Council such works as I imagine it may soon be in their power to have carried out by certain portions being done year by year until the whole would be complete, and the city effectually drained. The want, of a complete and thorough system of. sewerage has not been found to affect the health of the inhabitants of towns, as in Lincoln and Nottingham, &c., in England; and the enormous expense attending the construction of such works as would he required in Christehurch preclude the possibility of its being undertaken here for many years to come. Annexed is an appendix, shewing the estimated cost of the various works referred to in the foregoing. I have, &c., Wm. Fredic. Moore, City Surveyor, Christehurch. To the Gentlemen of the City Council, &e., Christehurch. Appendix to tiie Report —Stone kerbing, assisted by voluntary contributions, £5 10s per chain, stone kerbing, without voluntary assistance, £11 do; paving side channels, hammer dressed pitch stone, £17 do; pipes and cost of laying, £20 do; covered drain, Ferry lioad, £150 do; length 120 chains. Sewers as suggested, £150 per chain; length south part 130 chains, length north part 35 do, covered drain, do do 25 do; £100 per chain. Each dam across the Avon, £300. The estimated cost of a complete system of sewerage, with all appliances, &c., £700,000 (approximate).