Municipal and Official Handbook of the City of Auckland, New Zealand/Drainage Board
AUCKLAND AND SUBURBAN DRAINAGE BOARD.
When the necessity for drainage facilities first presented itself to the inhabitants of Auckland and the suburban areas, it was, of course, impracticable to proceed with extensive works. The authorities concerned therefore adopted the simple method of constructing sewers alongside the natural watercourses with the outlets discharging into the harbour. These sewer outlets were increased in number from time to time with the growth of the City and expansion of its suburbs, until it became apparent that some improved method of sewage disposal should be adopted.
As early as 1878, Mr. W. Clark, M. Inst. C.E., of London, visited Auckland for the purpose of reporting on the main drainage of the City and certain suburbs. In his report to the City Council he recommended the construction of intercepting sewers, pumping stations, septic tanks and filters with an outfall in St. George's Bay and provision for an extension to Hobson Bay if occasion should require. No action was taken however with regard to these recommendations.
In 1902 Mr. A. A. Wrigg, City Engineer, was instructed by the City Council to report on the drainage of the City. He advised that the method, then existing, of discharging sewage from the many outlets into the harbour could be rendered quite sanitary by the extension of the sewers to low water mark.
OKAHU BAY, SHOWING THE STORAGE TANKS.
After having considered Mr. Mestayer's report the City Council, under the Mayoralty of the Hon. E. Mitchelson, referred the whole question to Mr. G. Midgley Taylor, M. Inst. C.E., of London. In 1905 Mr. Taylor submitted his report, in which he recommended the utilization of the existing sewers as far as practicable and the construction of a main intercepting sewer with an outfall at Okahu Point.
In 1906 Mr. W. E. Bush, M. Inst. C.E, City Engineer, was instructed to report on the schemes proposed by Mr. R. L. Mestayer and Mr. G. Midgley Taylor. In his report to the Council Mr. Bush concurred with the proposals of Mr. Taylor, but recommended the adoption of a scheme which would provide for the drainage, not only of the City, but also of those suburban districts whose natural drainage was towards the Waitemata Harbour between Okahu Point and Motion's Creek.
This report was afterwards considered at several conferences of the authorities interested in the proposals contained therein. Mr. Bush was eventually instructed to prepare a scheme for the main drainage of Auckland and suburbs, the Auckland Harbour Board being at the same time requested to allow of the discharge of sewage at Okahu Point.
Subsequently Mr. G. Midgley Taylor was, by mutual agreement between the City Council and the Harbour Board, commissioned to proceed to Auckland and submit a further report. He visited Auckland in 1908 for this purpose, and his report on that occasion contained the following important recommendations, which became embodied in the scheme ultimately decided upon and authorised by Act of Parliament:—
(a) Adoption of a joint scheme for Auckland City and suburbs
(b) Drainage on the combined system.
(c) Direct discharge of the sewage, after screening, into the sea at Okahu Point.
(d) Adoption of the line of the main intercepting sewer recommended by the Board's Engineer, Mr. W. E. Bush.
At this juncture it was fully recognized that the scheme, if adopted, should be proceeded with under the control of a single authority. Proposals were therefore projected, and considered at some length, for the incorporation of a Greater Auckland Municipality to comprise at least those authorities concerned in the main drainage scheme. This was not effected, however, and as an alternative the scheme was authorised by "The Auckland and Suburban Drainage Act, 1908," and the Auckland and Suburban Drainage Board was constituted thereby as from October 10th, 1908.
The Board consists of the Mayor and Councillors of the City of Auckland, and the respective Mayors and Chairmen of the other contributing authorities; the Mayor of the City of Auckland being chairman of the Board, ex-officio.
The first meeting of the Board was held on November 20th, 1908, and was presided over by Mr. (afterwards the Hon.) Arthur M. Myers.
On October 25th, 1909, the works in the scheme were formally inaugurated by Mr. C. D. Grey, then Chairman of the Board. Upon completion of the outfall works at Orakei the scheme was brought into operation, the official opening ceremony being performed at the works on March 25th, 1914, by Mr. (afterwards the Hon.) C. J. Parr, C.M.G., then Chairman of the Board.
The function of the Board is to provide all necessary facilities for the reception of sewage from the several districts incorporated within the Drainage District, and to make provision for the proper discharge of such sewage into the harbour at Okahu Point. Reticulation sewers are provided by the several local authorities, by-laws of the Board regulating their design and construction.
The scheme has been designed for an area of 18,900 acres with an estimated ultimate population of 280,000 persons on a basis of 210 gallons per capita per diem, or six times a dry-weather flow of 35 gallons.
At the inception of the Board twelve separate districts were incorporated in the Drainage District with a total area of 12,915 acres. Portion of another district, comprising 2,240 acres, was incorporated in 1915, making a total area of 15,155 acres. Seven of the original districts have since been amalgamated with Auckland City, and have consequently ceased to exist as separate districts under the jurisdiction of the Board. The areas of the several districts incorporated in the Drainage District as at March 31st, 1921, are as follows:—
| District | Acres. |
| Auckland City (including Domain) | 1,878 |
| Parnell, amalgamated Auckland City, Feb. 15, 1913 | 684 |
| Arch Hill, amalgamated Auckland City, April 1, 1913 | 154 |
| Grey Lynn, amalgamated Auckland City, July 1, 1914 | 900 |
| Remuera, amalgamated Auckland City, March 1, 1915 | 2,520 |
| Eden Terrace, amalgamated Auck. City, Oct. 1, 1915 | 95 |
| Epsom, amalgamated Auckland City, Feb. 1, 1917 | 860 |
| Pt. Chevalier, amalgamated Auck. City, Mar. 1, 1921 | 1,200 |
| Total area Auckland City | 8,291 |
| Mount Eden | 1,400 |
| Mount Albert | 2,450 |
| Newmarket | 169 |
| One Tree Hill (portion) | 605 |
| Avondale (portion), incorporated Nov. 4, 1915 | 2,240 |
| Total area Drainage District | 15,155 |
The further area of 3,045 acres provided for comprises an additional area of the One Tree Hill Road District, the Orakei Road District, and a portion of the Mount Roskill Road District. Negotiations have been commenced for the inclusion of the first-mentioned area, but no proposals have yet been made with respect to the other two areas.
In the census returns for 1911 and 1921 the population of each of the several districts is given as follows:—
| District. | Population | ||
| 1911. | 1921. | ||
| Auckland City (including Domain) | 67,832[1] | 81,712 | |
| Mount Eden | 9,381 | 14,635 | |
| Mount Albert | 6,700 | 11,345 | |
| Newmarket | 2,780 | 3,083 | |
| One Tree Hill (portion) | 2,000 | 5,197 | |
| Avondale (portion) | [2] | 3,229 | |
| 88,693 | 119,201 | ||
The Board is empowered to borrow a total sum not exceeding £500,000 for expenditure on the works authorised. At March 31st, 1921, five separate loans had been effected amounting in all to £450,000. Two loans, amounting to £5,500, raised by the late Hobson Bay Watershed Sewage Board, are also liabilities of the Board, the public debt of which ts therefore £455,500.
Repayment of loans is provided for by a sinking fund administered by the Auckland and Suburban Drainage Loan Commissioners. The accumulated amount in the fund at March 31st, 1921, was £25,436 15s.
The ordinary income and revenue of the Board is derived by assessments levied annually upon the contributing authorities. The fund thus created provides for the payment of interest and sinking funds on loans and for expenses incurred in general maintenance of completed works. An annual estimate of the amount required for these purposes is prepared, and each local authority is assessed for its proportion of this amount as the capital value of all the ratable property in its district bears to the total capital value of the Drainage District, these values being furnished by the Valuer-General. The following table shows particulars of these operations for the year ending March 31st, 1921:—
| District. | Capital Value[1] | Amount Assessed. | |||
| £ | £ | s. | d. | ||
| Auckland City | 21,868,377 | 22,081 | 2 | 4 | |
| Mount Eden | 2,302,815 | 2,325 | 4 | 3 | |
| Mount Albert | 1,635,418 | 1,651 | 6 | 6 | |
| Newmarket | 661,404 | 667 | 16 | 9 | |
| One Tree Hill (portion) | 663,457[2] | 669 | 18 | 2 | |
| Avondale (portion) | 387,464[2] | 391 | 4 | 8 | |
| [3]Point Chevalier | 242,150 | 244 | 10 | 1 | |
| £27,761,085 | £28,031 | 2 | 9 | ||
The following principal works in the scheme were completed at March 31st, 1921:—
(a) Outfall works at Orakei, comprising outfall sewer, storage tanks, buildings and plant.
(b) 7 sections of the main sewer of a total length of 8 miles 10.5 chains.
(c) 13 branch sewers of a total length of 12 miles 73.2 chains.
(d) 4 pumping stations.
MAIN BUILDING, IN WHICH SCREENING PLANT IS INSTALLED.
two 48in. diameter cast-iron pipes on cast-iron cradles, the next length of 324ft. consists of two similar pipes set in concrete, and the remaining portion is a concrete culvert 22.5 square feet in sectional area leading into the outfall chamber of the storage tanks. The invert of the outfall sewer at its point of discharge is 26.2ft. below high-water level.
The storage tanks are comprised in one block 1,296ft. 6in. in length and 106ft. wide, with a total capacity of 7,800,000 gallons. They are constructed of concrete, plain and reinforced, the roof having been designed to form a portion of the suggested esplanade for the foreshore of the harbour.
At the inlet end of the tanks a brick building is erected in which is installed the screening and detritus-removal plant, comprising coarse screens, mechanically operated fine screens, and a bucket dredge. This plant is driven by a 10 b.h.p. vertical steam engine, with an oil engine as a stand-by. A valve chamber is built at the outlet end of the tanks, in which the valves controlling the discharge of sewage are operated.
The main intercepting sewer, which has a ruling gradient of 1 in 3,000, is of the standard oviform, or egg-shaped section, ranging from 8ft. 6in. by 5ft. 8in. to 3ft. 6in. by 2ft. 4in. It is constructed of concrete, plain and reinforced, and is laid principally in tunnel with the exception of a length of 100 chains in Hobson Bay, which is constructed on reinforced concrete piles. The branch sewers are of various sections and grades, and are constructed of concrete and earthenware pipes.
MECHANICAL SCREENS: FRONT.
MECHANICAL SCREENS: BACK.
Four pumping stations have been provided for the low-level areas and reclaimed lands on the foreshore of the City. The plant necessary for the total output at each station is installed in duplicate, each unit consisting of a stereophagus centrifugal pump, electric motor, patent automatic controller and float apparatus.
During the year ending March 31st, 1921, an average daily dry-weather flow of 6¾ million gallons was recorded at the Orakei works. The greatest quantity discharged in any one day was 57½ million gallons, recorded on November 22nd, 1915.
The Board meets quarterly in the Council Chamber, Town Hall, Auckland. The successive Chairmen of the Board have been Mr. (afterwards the Hon.) A. M. Myers, 1908–1909; Mr. C. D. Grey, 1909–1910; Mr. L. J. Bagnall, 1910–1911; and Mr. (afterwards the Hon.) C. J. Parr, C.M.G., 1911–1915; the present Chairman being Mr. J. H. Gunson, C.M.G., who has held that office since April, 1915.
The office of the Board is in Cleave's Buildings, High Street, Auckland. Mr. W. E. Bush, M. Inst. C.E., City Engineer, who designed the scheme, was Engineer to the Board until September, 1915, and Mr. R. H. Erwin was Secretary to the Board until April, 1914. These officers were succeeded by the present holder of the joint position of Engineer and Secretary.