DRAINAGE 



DRAINAGE 



1075 



coarser crushed stone and fine cruched stone, over 

 which is spread a thin layer of washed sand. The 

 bottom of the drain ought to be approximately 6 inches 

 lower, at the point where the outlet to the sub-drain is 

 located, than the elevation at the extreme high points of 

 the drain. The method of establishing these grades varies 

 largely with the requirements of 

 this particular problem. The 

 water, as it reaches the low 

 point in the drain, is conducted 

 at once into the main 6-inch 

 drain, which also takes ground- 

 water from the underground sys- 

 tem of drains. When the court 

 is so constructed that one end is 

 lower than the other, in order 

 to assist surface-drainage condi- 

 tions the courts should be level 

 from side to side. Fig. 1357 

 shows the general distribution of 

 the system of tile to care for 

 the sub-surface water in tennis- 

 court construction. This would 

 apply equally well to the con- 

 struction of other recreation 

 areas, including clock- golf - 

 greens, bowling-greens and cro- 

 quet-lawns. In the construction of all tennis-courts, 

 the trenches excavated for the tile should be filled with 

 cinders or an equally porous material to a height not 

 less than 6 inches below the proposed finished grade 

 of the court. 



Clock-golf-greens, bowling-greens, and croquet-lawns. 

 A thorough distribution of tile drains installed as out- 

 lined below, should meet all the requirements commonly 

 imposed from the drainage standpoint upon the con- 

 struction of these recreation areas. Lines of 4-inch tile 

 should be placed, at intervals of not more than 10 feet. 

 For the most thorough and ideal drainage of these 

 areas, provided the cost is not prohibitive, the con- 

 struction would be as follows: A neat sub-grade should 

 be made at a depth not exceeding 15 to 18 inches below 

 the proposed finished surface of the recreation area. 

 The necessary lines of tile should be laid in trenches at 

 a depth varying between 2 and 2^ feet below the finished 

 grade, these trenches to be filled with cinders, crushed 

 stone or gravel (Fig. 1355). On this sub-grade, thus 

 completed, the entire recreation area should be filled to 

 a point approximately 6 inches below the proposed 

 finished grade, with cinders, or some equally porous 

 material. On this finished surface, the remaining 6 



middle of the road is used in soils in which the ground- 

 water level is abnormally high. Such drains should 

 range in depth from 2 to 3^ feet below the finished sur- 

 face of the road, and the trenches should be filled with 

 a porous material and not with the natural soil. The 

 method of installing drainage under the sides of the 





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~~T LATERAL d( >K 'Alt 



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1357. Draining a tennis-court. 



road, as shown in Fig. 1358 is used in heavy clay soils, 

 and serves to keep the foundation of the road on well- 

 drained soil. These drains are installed at a depth 

 varying from 2 to 3 feet in trenches filled with cinders or 

 equally porous material. 



Turf pleasure roads, so frequently constructed on 

 private estates, should be thoroughly drained with a 

 Line of tile placed under the middle of the road, unless 

 the road is constructed on a heavy foundation of field- 

 stone or gravel which forms a natural drain path for 

 surface-water and soil-water. 



In providing drainage along the sides of roads con- 

 structed on clay soils through virgin woods, it is some- 

 times necessary to carry these drainage lines a con- 

 siderable distance through the woods to suitable out- 

 let points. The joints of all such lines of drainage 

 should be cemented, otherwise the artificial condi- 

 tions produced by the increased drainage will work 

 serious injury to many large trees growing on either 

 side. In general it is very unsafe to install drainage 

 lines through virgin woods, without this precaution. 

 Roads constructed through such woods would better 

 be drained by laying a line of tile under the middle of 

 the road as shown in Fig. 1359. 



inches should be filled with a layer of loam free from 

 clay, but composed of a small percentage of sand. 

 In this way, a firm surface will be obtained which will 

 readily care for any surface and subsoil water. 



5. Roads. 



The secret of a perfect road surface lies (1) in the 

 proper crown of the road, and (2) in the adequate 

 drainage of the subsoil or foundation. The first pro- 

 vision cares for the surface water, and the second 

 provision eliminates any surplus ground-water. 



On all private estates on which roads are constructed 

 on heavy clay soils and not on grades greater than 4 

 per cent, the secret of success depends upon drainage 

 installed in either of the two ways shown in Fig. 

 1358 or Fig. 1359. Installing a line of drains under the 



4. Walks. 



A i t 



A most irequent 

 method of provid- 

 ing drainage for 



walks is that shown in Fig. 1359. A line of 4-inch tile 

 is laid at a depth varying between 18 inches and 30 

 inches below the finished grade of the walk and fol- 

 lowing the middle line of the walk. The trench for the 

 tile is filled with a porous material to a height even 

 with the bottom of the cinders used for the founda- 

 tion of the walk, or laid as shown in Fig. 1359. 



6. Newly planted trees. 



All trees planted in clay soil require drainage. If 

 the pockets in which such trees are planted are not 



