HISTORY OP CIVIL ENGINEERING IN NEW SOUTH WALES. 647 



the southern slopes, and portions of tlie following not included in 

 either the northern or soutliern systems — namely, Petersham, 

 Newtown, Leichhardt, Macdonaldtown, and Alexandria. Tlie 

 scheme for the drainage of the Western Suburbs has been 

 thoroughly considered by Mr. G. Stayton, M. Inst. C.E., and in 

 a report published in the early pai't of this year he proposes to 

 construct an outfall sewer commencing at Webb's Grant at a spot 

 about twenty chains east of Muddy Creek, and, after passing 

 through the additional land proposed to be resumed, the route 

 selected would enable the sewer to pass under the two main roads, 

 and the lUawarra railway at Tempe in tunnel, across WoUi Creek, 

 through Unwin's Hill, in tunnel under the high ground on the 

 west of the " Warren," terminating in a penstock chamber at the 

 junction of the intercepting sewers in Premier-street, the length 

 being two miles three hundred and eighty yards. Some parts of 

 this outfall sewer will be raised above the level of the surface in 

 an embankment ; whilst in others it will be carried by aqueducts 

 over creeks, swamps, and flats. At the crossing of Cook's River, 

 the level of the bottom of the sewer will be at least fourteen feet 

 above high-water mark. The invert level at the outfall is nine 

 feet above high-water mark, which will command filtration through 

 at least six feet of earth at any portion of the western part of the 

 sewage farm. The distance from the outfall to the penstock 

 chamber in Premier-street is eleven thousand seven hundred feet, 

 and as the intended grade is one in seven hundred, or 3.11 feet 

 per mile, the invert at the intercepting chamber will thei'efore be 

 15.88 above high-water mark. Mr. Stayton says that the estimated 

 maximum flow is thirteen thousand nine hundred and ninety-seven 

 cubic feet per minute, which would require a sewer nine feet in 

 diameter. He recommends, however, three sewers each six feet 

 in diameter for various practical reasons, and for the present one 

 of these sewers will be sufficient, but it would be advisable to 

 construct the outfall sewer in duplicate. For the effectual drainage 

 of the western area, it will be necessary to provide for the con- 

 struction of four intercepting sewers, all of which will commence 

 at the penstock chamber already referred to. In order that the 

 low-lying districts may be included in the system, pumping engines 

 will be erected at Marrickville to raise the sewage up to the level 

 of the intercepting sewer of the districts. There are several other 

 low-lying districts, such as portions of the Glebe, Leichhardt, 

 Balmain, Ashtield, Five Dock, Burwood, Concord, and Strathfleld, 

 which will require to be provided for by some method of raising 

 the sewage to the level of the intercepting sewers, such as the 

 hydro-pneumatic system, which has been in operation in Eastbourne 

 and Southampton in England with very satisfactory results. The 

 sewage delivered by the outfall sewers at Webb's Grant will be 

 disposed of on the sewage farm in a similar manner to that of the 

 southern section. Mr. Stayton has thoroughly considered and 



