44 DESIGN 



times be used to advantage where dislocations might other- 

 wise occur. 



1. Storm=water Sewers. The peculiar features of park 

 storm-water sewers are the methods of collecting the water, 

 the methods of discharging it and the calculation of size. 



Methods of Collection. In order to collect storm water, 

 inlets and catch-basins must be constructed. 



The inlet is merely an opening for the admission of 

 water. It consists of an iron grating set in concrete over 

 a 6-inch elbow from which the water is carried by a 6-inch 

 chute into a catch-basin or directly into the sewer. 



The catch-basin is usually built of brick, of circular 

 horizontal section and surmounted by a grating to provide 

 for the entrance of rain water and the exclusion of sticks 

 and leaves. It is constructed about 6 or 7 feet deep, 

 4 feet inside diameter, corbeled in at the top to a diameter 

 of 2 feet. The cast-iron grating is rectangular for paved 

 gutters and circular for grass gutters. Its height is about 

 8 inches. It is cast in two pieces the lower part provided 

 with a flange to rest upon and a grating to hold back 

 obstructions. A catch-basin is provided with a concrete 

 foundation about 6 inches thick. The invert of the outlet 

 pipe, which is 6 inches in diameter, is about 3 or 4 feet from 

 the bottom. No outlet trap is provided, the purpose of 

 the catch-basin being merely to catch mud and gravel and 

 prevent its entrance into the sewer. 



Instead of placing two catch-basins on opposite sides of 

 a path or drive, it is often well to dispense with one and 

 build an inlet instead. The inlet discharges into the 

 catch-basin and the catch-basin into the sewer. Should 

 the inlet or its chute become stopped, it may be cleaned out 

 by use of a garden hose. 



Catch-basins and inlets can be placed in paved gutters, 



