I find that the maximum depth of the Western intercepting sewer at the pumping station just behind Kennedy Town would be about 10 feet below O.D. or 22 feet below ground. This is by no means an extravagant depth.
781
intercepting
recommend-
an
13. I have brought forward the question of complete interception mainly The cons- because I contemplated the possibility of its having to be adopted in Reports made inction of in 1890, and arranged the design of sewers in a manner that would permit of its sewers not adoption. I look upon the construction of intercepting sewers as a counsel of per- ed as aate fection. I do not recommend even the consideration of this project at the present work. moment. There are many other costly works, notably those for the augmentation of the water-supply, that must take precedence of any radical alteration of.the sewerage system. I maintain that if matters remain in statu quo, no danger to the public health is involved.
There may be occasional nuisance, and, undoubtedly, the necessity for pe- riodical cleansing by means of chains and drags is a source of expense. But this is the worst that can result from the defects that I have noted. The said nuisance will not give rise to epidemics of disease and is of little moment, compared with the water famines which occur almost annually necessitating the introduction of the intermittent system.
connection
with the low-
level sewers.
14. The only works that need be contemplated for some years to come, in The works connection with the low-level sewers, are the re-laying of the sewers on the New required in Praya Reclamation in all cases in which settlement has caused detrimental distortion and alteration of the originally projected level. This work should, however, be deferred until the New Reclamation has thoroughly settled, so that no further movement need be anticipated. Some sewers on even the Old Reclamation will require re-laying, notably those leading to the No. 1 outfall at Belcher's Point. Notwithstanding the fact that the Praya Wall in this locality was constructed many years ago, there is evidence to shew that settlement has taken place relatively recently, and that it may be going on even at present.
15. The recommendations which I have made, with regard to street sewers, Summary of in this and a previous report, may be summed up as follows:-
(a.) Complete the outfall sewers across the New Reclamation.
(6.) Prevent by means of additional care in scavenging the introduction
of improper solids into the street sewer.
(c.) Trap all street sewer gulleys with improved traps and gratings. (d.) Make an experiment as to the effect of vigorous flushing at low tides with well or sea water, on one section of the low-level sewers. If this experiment is successful, and leads to saving in working expenses, extend the same system to other sections.
(e.) Close the ventilating openings in the sewer manholes. (.) If, contrary to expectation, ventilating openings or rather vents prove necessary let them be provided, either by means of the house sewer ventilating pipes, removing the intercepting traps, or by providing separate elevated vent-pipes carried up above the neighbouring buildings as suggested in a previous report.
(9.) Whenever the roots of trees cause obstructions, cut down the trees; or substitute cast iron pipes, with lead and yarn joints for stone- ware pipes.
HOUSE SEWERS.
It has come to my knowledge that considerable inconvenience has been experi- enced in the case of European houses in the upper levels of the City. These tene- ments are provided with a drain, as defined in my former report, as well as a house sewer, and it frequently happens that the grating over the inlet to the house sewer becomes obstructed and, in consequence, the sewage, properly so called, flows into the nullahs, causing a nuisance. It is difficult to suggest a compléte remedy for this, for the arrangement must vary in each individual case. After all, the
recommend- ations with regard to street
sewers.