RECORD OF TESTIMONY AND STATEMENTS IN RELATION TO 173 



NECESSITY FOR DISTRICTING PLAN 



ings usually occupied a smaller percentage of the lots and the portion not 

 occupied by buildings was cultivated as a garden or a grass plot, whereas 

 at present the back lots, in the most populated sections of the city at least, 

 are paved with an impervious material such as bluestone, cement or asphalt. 

 It was, therefore, quite ' proper that the sewers should have been 

 designed for a considerably smaller run-off of rainwater than at present. 

 In consequence of these conditions and the more or less inaccurate theory 

 of sewer design based upon them a great many of the sewers which were 

 built at that time are inadequate for present requirements, so that during 

 heavy storms property is frequently damaged on account of the backing up 

 of the sewage through house drains. In fact, there are some locations 

 in the citv where in excessive storms the sewers overflow on the surface of 

 the street and over the sidewalks. 



Need of reconstruction of sewers 



It will be seen, therefore, that there is need of reconstruction of sewers 

 in the older portions of the city for the two reasons hereinbefore described, 

 namely, on account of deterioration and on account of inadequacy. 



Redesign of drainage areas 



Before a general reconstruction of the sewers can be undertaken it will 

 be necessary to redesign the drainage areas and provide for sizes and grades 

 of sewers in accordance with the changed conditions and the present science 

 of sewer design. 



This practically means the installation of a new sewer system, because 

 it will readily be seen that very few of the older sewers can be incorporated 

 in the new system. Of course it is not the purpose, when the reconstruction 

 of sewers is undertaken, that all existing sewers should be dug up regardless 

 of their physical condition, but it is the purpose to bring about this change 

 gradually, as the sewers deteriorate or are inadequate. 



Pollution of the harbor 



Since the time that New York City has used the present water carriage 

 system of sewers, the sewage has been discharged into the adjacent waters 

 of the harbor without any treatment, with the exception of a few installa- 

 tions in the Boroughs of Brooklyn and Queens. The purification plants in 

 these boroughs have been constructed comparatively recently and they treat 

 a very small percentage of the total volume of sewage which is discharged, 

 so that their influence upon the pollution of the harbor is comparatively 

 insignificant. 



The harbor waters, therefore, are more or less saturated with the 

 sewage which has been discharged into them during the last 75 or 100 years. 

 In some of the more confined portions of the harbor, such as the East 

 River and the Harlem River, where the tidal movement does not extend to 

 the purer waters of the Sound or the ocean, this pollution is so great that 

 offensive putrefaction is liable to set in at any time under favorable 

 conditions. 



Purification of the sewage 



In the design of a new sewer system it will therefore also be necessary 

 to take into consideration the purification of the sewage before it is dis- 

 charged into the harbor. The City of New York is practically committed 

 to a general purification of its sewage, although this may not be -necessary 



