300 



SOME MUNICIPAL ENGINEEKING I'KOHLEMS IN THE TKOl'lCS 



Construction 

 of percolation 

 pits 



Latrines and 

 Urinals 



of a hole in the groimd about 4 feet square and 4 feet 9 inches deep tilled to 

 a depth of 4 feet with broken stone. This is covered over with rough boarding and 

 the surface of the ground restored, the object of the ' boarding being to prevent the 

 stone becoming choked by surface soil washing down and filling up its interstices. The 

 waste water trickles down through the stone and percolates into the surrounding ground, 

 wliile the accumulation of grease and other foul matter is rendered inoffensive by bacterial 

 action, as in the case of an ordinary cesspit. If the waste is discharged direct into the pit 

 by a pipe communicating with the sink, a ventilation shaft is required to obviate the risk of 

 foul gases finding their way back into the house, but if the waste discharges into an open 

 channel and thence by a pipe into the pit this precaution is not necessary. In this latter 

 case there is a certain danger of mosquitoes going down the short length of pipe and 

 breeding out in the percolation pit and, to overcome this difficulty, the type of pit shown 

 in Fig. 93 has been designed. In this type the entry of mosquitoes is prevented 

 by means of a self-closing flap on the end of the discharge pipe which terminates in a brick 

 inspection shaft so that the flap valve can be examined and cleared when necessary. This 

 type has not been long in use, but so far has worked satisfactorily. 



Fig. 94 shows the general system of waste water disposal installed for each of the 

 two bungalows referred to under Section III (Fig. 91). The bath waste is discharged into 

 the cement channel A' which has openings in the side for irrigation. The waste from the 

 sinks B and C is connected by pipes and channels to the percolation pit and a small sluice 

 is fitted at E so that the bath water may be discharged into the pit when required, either 

 to flush out the channels and pit or when it is not wanted for irrigation purposes. 



Care must be taken not to place these pits too near to the foundations of boundary 

 walls or buildings, especially in localities such as Khartoum where the soil is of an alluvial 

 nature and becomes soft and plastic when saturated with water. 



(3) Waste-water pits 



In certain oases in the business part of the town where considerable quantities of 

 water are used and there is no ground available for irrigation and a percolation pit 

 is undesirable owing to the proximity of buildings, waste-water pits have been used. 

 Fig. 95 shows the general arrangement of one of these waste-water pits. They are of 

 water-tight construction, cement-rendered on the inside, and are provided with a water seal 

 and ventilation shaft and fitted with a close iron cover. Their contents are removed daily 

 beyond the town limits by special carts fitted with a discharge pipe and valve in the 

 bottom. As in the case of percolation pits the consti'uction of these waste-water pits has 

 to be approved by the Sanitary Authority, and permission is only given in cases of 

 absolute necessity, as the labour and expense of emptying them is considerable. 



It is, of course, recognised that the present system of waste water disposal cannot be 

 indefinitely extended and must be looked upon more or less in the light of an expedient, to 

 be continued until such time as the development of the town and other circumstances 

 warrant the introduction of a proper water carriage sewerage system. 



In "Sanitary Notes," by the Medical Officer of Health, in the Third Eeport,' the 

 type of public latrines in use in Khartoum was illustrated and described, and similar 

 latrines have now been erected at Khartoum North and Omdurman. 



A certain number of public urinals have been found necessary, and these, which are a 

 modified Indian type, are illustrated in Fig. 98. They were at first constructed 

 without any wash pit, and it was found that both the latrine floor and the surrounding 



' Third li^mrt, Wellcome Tropical Research Laboratories, Khartoum, 1908. 



