Practical suggestions by Mr. Rogers Field, M. Inst. C.E., as to water supply, drainage, and sewage disposal for lunatic asylums / issued by the Commissioners in Lunacy.

  • Field, Rogers.
Date:
1892
Catalogue details

Licence: Public Domain Mark

Credit: Practical suggestions by Mr. Rogers Field, M. Inst. C.E., as to water supply, drainage, and sewage disposal for lunatic asylums / issued by the Commissioners in Lunacy. Source: Wellcome Collection.

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    6> o afe two main considerations which should never bo Forgotten. First, there is the question referred to above of the direction >of the flow of the underground water, whether it is from or towards a possible source of contamination, Secondly, there is the question of the effect produced by pumping. The latter is so important that it requires special notice. (9.) When considerable quantities of water are pumped from a well not only is the water lowered in the well itself, and in the porous strata immediately surrounding it, but the under¬ ground water at a considerable distance is affected and gradually drawn towards the well. A funnel-shaped depression is thus created in the underground water, and the depth of this depres¬ sion and the distance to which it extends around the well will increase with the quantity of water pumped from the well. Consequently a well which may be quite safe from pollution, when only a small quantity of water is drawn from it, may be unsafe when large quantities are drawn from it, a3 in the latter case the sphere of influence will be largely extended. (10.) If water collected from springs is used for the water supply the question of possible pollution of the underground water must of course be considered as in the case of wells. It is also important to bear in mind that the amount of water yielded by the spring will have a seasonal variation, generally yielding least in autumn and most in the early part of the year. The only safe way therefore to estimate the amount which a spring can be depended on to supply is to have a series of gaugings taken extending over a considerable period, including the autumn, so as to ascertain the minimum yield during the year. Attention must also*be paid to whether the season immediately preceding the gaugings has been unusually' wet or dry. If the previous season, especially the winter, when percolation chiefly takes place, has been unusually wet, the yield of the spring in the ensuing autumn may be higher than usual, and thus be far from representing a true minimum. (11.) Water collected from gathering grounds is frequently adopted as a source of supply in the case of towns, but it is not generally available or desirable for asylums. There may, how* ever, be instances where it could be adopted with advantage, and in such cases some of the chief points to be attended to are as follows:— (a.) The gathering ground from which the water is collected should be such that there is no danger of the water being polluted from sewage or manure or the droppings of cattle or any other source. Hardly any land except uncultivated ground, such as is found in mountainous districts, will fulfil this condition. (b.) The gathering ground must be sufficient in extent to supply the required quantity of water in the driest year. In calculating the quantity of water that is required, it will generally be necessary to take into Effect of pumping on possibility of pollution. Water col¬ lected from springs. Water col¬ lected from gathering grounds.