. Bulletin of the Department of Agriculture. Agriculture; Agriculture. EARTH, SAND-CLAY, AND GRAVEL ROADS. 15 approximately smooth slope, as is done in earth cuts. In excavating solid rock only such material is moved as is actually necessary to obtain the desired width at the bottom of the cut or as has been loosened in blasting. The faces should, of course, be cleared of all material which is loose, or which might be loosened subsequently by frost and slide down upon the road. Stone embankments will stand on a slope of about 1 to 1. In order to prevent damage by washing all earth slopes
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. EARTH, SAND-CLAY, AND GRAVEL ROADS. 15 approximately smooth slope, as is done in earth cuts. In excavating solid rock only such material is moved as is actually necessary to obtain the desired width at the bottom of the cut or as has been loosened in blasting. The faces should, of course, be cleared of all material which is loose, or which might be loosened subsequently by frost and slide down upon the road. Stone embankments will stand on a slope of about 1 to 1. In order to prevent damage by washing all earth slopes in either excavation or embankment should be protected by a growth of grass as soon as practicable after they are formed. In many localities where the soil is fertile and a good quality of grass is native no seeding of the slopes is necessary. In other cases the soil may not possess sufficient fertility to grow grass, even when the slopes are seeded, and in which event it may be very desirable to cover the slopes with cut sod. This latter process usually is very expensive, and should be employed only where it is known that thorough seeding and fertilizing would fail to secure a covering of sod. Another precaution frequently necessary in order to prevent the washing away of excavation slopes is to intercept water from the. CROSS SECTION SHOWING BERM DITCH BUILT ABOVE SLOPE ^Dimensions of the ditch are determined by the amount of water to be carried C is generally 18 to 24" and "G" a bout 12". Fig. 10. natural ground surface which otherwise would flow down over the excavation slope. This is done by means of a " berm " ditch con- structed well back from the top of the slope. Figure 10 illustrates a condition which makes a " berm " ditch desirable and also shows how such a ditch is constructed. EARTH Roads constructed by grading the natural soil to the required shape, grade, and alignment, without special surfacing of any kind, are de
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