Surface water from a bazaar is classified as sullage.
FIG. 9.
Where tanks are used as a source of drinking water-supply, they should be properly fenced and conserved, and the water drawn by a pump. Recent researches have proved that polluted water, if stored in a tank or reservoir where it can be preserved from subsequent contamination, rapidly becomes pure. The Type plan, approved by the Sanitary Board of Behar and Orissa, is shown in Fig. [9], page [13]. This for an existing tank of 100 yards square area is estimated to cost Rs. 2,700. The pumps, provided in duplicate, are Kite double action pattern and cost about Rs. 425 each. The fencing provided is the Ideal Woven wire fence, 10 strands, 48″ high, and can be fixed at about 12 annas per yard.
Another and a cheaper method is shown in Fig. 10, page [15]. Here the tank is completely fenced in with the exception of an entrance to a platform which extends towards the centre of the tank from which the water can be drawn by hand. Model rules for clearing out and re-excavating tanks are as follows:—
Excavation.
1. Tanks should be cleared out and re-excavated during the dry weather months when the level of the subsoil water is at its lowest. Work should be commenced in January or February and completed before the middle of May, but these dates must depend more or less on the locality, as in some parts of the Province the prevalence of heavy thunderstorms in May might make it advisable to complete the work before then.
2. The re-excavation, until water-level is reached, should be carried out in regular layers of 1 foot in depth, an offset of 1 foot being left on the bank side for each layer. This, when dressed off, will give a regular side slope of 1 to 1 to the tank. When water-level is reached, if it be considered necessary to excavate below this, and if pumping machinery to dewater the tank is unavailable, the area must be divided up into compartments of suitable size, separated by bunds, one, or more of which, can be dewatered by bailing into the adjacent ones, when the excavation can be continued to the required depth, the other compartments being similarly treated in turn.
TYPE DESIGN FOR FENCING IN TANKS
FIG. 10.