CONSTRUCTION NOTES 275 



the concrete in place. The width of the gutter, depending upon the type 

 of material used for the surface of the road, may vary from eight to 24 

 inches inside of the face of the curb. Concrete mixed in the proportion of 

 1 : 2^2 15 is placed in the gutter and tamped until water comes to the surface 

 and the concrete has assumed an even surface about one inch below the 

 finished surface of the gutter. Before this concrete has even commenced 

 to set, a coat of cement mortar one inch in thickness is spread on top, 

 bringing it to true finished grade. This cement mortar should be mixed in 

 the proportion of one part cement to two parts sand. In many cases it is 

 desirable to darken this coat, which is accomplished by adding a one- 

 pound package of lampblack to each two bags of cement. The same methods 

 of curing and of protection should be adopted as are recommended for 

 concrete curbs. It is very important that the individual sections of com- 

 bined curb and gutter (approximately 6 feet each) should have expansion 

 joints every 25 or 30 feet; but it is also necessary that these should be 

 provided between the inner surface of the gutter and the road metal if 

 any other material than macadam is used. 



V. Turf Gutters. Turf gutters (Plate 113, figure i) are usually con- 

 structed in connection with private entrance drives. The width of turf 

 gutters ordinarily varies from four feet, six inches, to six feet or eight feet. 

 Where a large quantity of surface water is to be removed by the turf gutters, 

 the catch basins or other inlets should be located at frequent intervals to 

 minimize erosion or wash in the surface of the gutter. Turf gutters should 

 never be less than four inches in depth, and should be preferably six to 

 eight inches in depth. Unlike other types of gutters, the turf gutter should 

 be a part of the surrounding lawn area and, therefore, unnecessarily deep 

 and narrow turf gutters create an unattractive landscape effect. The 

 problem of maintenance requires that turf gutters should be designed so 

 that the average lawn mower can be used to mow the gutter lengthwise. 



With the subsoil thoroughly drained and the drainage trench filled 

 with compacted cinders to a height even with the surface of the finished 

 subgrade, the area of the gutter is subgraded so that the surface of the 

 subgrade is parallel with and about four or five inches below the proposed 

 finished grade of the gutter. The topsoil is then put in place, and if the 

 area of the gutter is to be sodded, an allowance for the depth of sod should 

 be made in making the topsoil fill. The most economical method of even- 

 tually securing a good turf on the average turf gutter is through seeding, if 

 the grade of the road or the slope of the adjacent bank does not create exces- 

 sive wash. Even if such conditions exist, it is sometimes more economical, 

 if seeding can be done at the ideal time in the spring or fall, to reseed por- 

 tions of the gutter one or more times than to incur the expense of sodding 



