XXX 



about one acre of suitable land — strong land is the best — is required 

 for each 100 of the population. The most successful sewage farm in 

 England is that at Beddington, where the sewage of 66,000 inhabitants 

 of the Croydon district is received on COO acres of land without any- 

 pumping being required. The yearly value of the land on this farm 

 has risen from £ 1 to £9 an acre. In my report it is calculated 

 that if 200 acres of suitable land could be found, say near the old 

 racecourse at New Town, or anywhere within three miles of Hobart, 

 the cost of the land, of the drainage, levelling, etc., would be £30,000, 

 the yearly interest upon which sum, together with maintenance, 

 pumping, etc., would amount to £2,800 a year, so that there would 

 be an annual first charge upon the land of £14 an acre, inde- 

 pendently of cest of cultivation, etc. If a sewage farm in the 

 immediate neighbourhood of the London market commands £9 an acre, 

 who would give £14 an acre for one here ? Consequently it may be 

 said that irrigation as a means of disposing of Hobart sewage is out of 

 the question. 



As before mentioned the arrangement of the outfall sewer proposed 

 is such that there is ample opportunity to apply to the sewage any 

 mechanical or chemical system of purification that may be found 

 desirable at any time. If such a system can be found that is not more 

 costly than it is worth, by all means let it be applied. But in the 

 meantime the allowing of the fresh sewage of Hobart to run into 

 the estuary of the Derwent, in the manner provided for in the 

 report, cannot cause any harm or inconvenience. In connection with 

 this subject will, you allow me to quote the following paragraphs from 

 my report : — 



OUTFALL ARRANGEMENTS — TIDAL ACTION. 



At the respective outfalls, arrangements would be made for discharging 

 when necessary at all states of the tide. Thus, if desirable, the sewage 

 could be discharged at about half ebb so as to insure its being 

 carried out of Sullivan's Co»e and Sandy Bay. This, however, would 

 only be necessary at the Battery Point outfall, and even there, the 

 harbourmaster tells me, it is only at exceptionally high tides that the 

 flood sweeps round into the cove. According to the Admiralty chart, 

 the half ebb runs down at 1J knots an hour opposite Macquarie Point, 

 while opposite Battery Point the half flood flows up at f of a knot 

 only. The harbourmaster thinks the latter rate overstated, as there is 

 usuually only flood enough to counteract the downward flow of the 

 river. However that may be, it is evident that there is opposite 

 Hobart an almost continuous downward current carrying water out 

 to sea, and that this so greatly exceeds any occasional upward flow of 

 tide as to remove any danger that sewage matter would be kept 

 floating up and down opposite Hobart. In this respect Hobart differs 

 from many other towns on tidal rivers, — Brisbane, for instance. In 

 dry weather the Brisbane River is not appreciably affected by 

 the downward current of fresh water from a comparatively limited 

 cateh-water basin, with a small rainfall. The upward flow of the tide 

 is apparently as strong as the downward ebb. Consequently the 

 Brisbane at the city has the character rather of a land-locked arm of 

 the sea than of a river, and sewage flowing into it would float up and 

 down until some strong freshet carried it away, and in the dry season 

 this might not occur for months. The effect of this in a sub-tropical 

 climate may be imagined. At Sydney, also, the Admiralty charts 

 show that the upward flow of the tide is equal to the downward ebb, 

 so that in position it resembles Brisbane ; therefore, the consequences 

 of the discharge of sewage at both places can never follow at Hobart. 

 There is still less resemblance between the conditions under which 

 this discharge will take place here and in the oft-quoted River Lea. 



