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Pioneering
Figure 15-66.Longitudinal drainage of runways.

Equipment Operator Basic - Beginning construction equipment operators manual
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been removed, refill the holes and level the area to prevent  the  accumulation  of  water. STRIPPING Stripping consists of removing and disposing of objectionable topsoil and sod. It may either follow or be   done   with   clearing   and   grubbing.   Actual earthmoving begins with stripping; surface soil and rocks  are  removed  from  the  area  to  be  excavated. Deeply  embedded  rocks  and  large  boulders  may  have to  be  blasted  before  they  can  be  removed. The material removed by stripping is called  spoil. Unless  otherwise  directed,  you  should  dump  spoil along the area to be excavated within range of the earthmoving equipment. If the spoil will not be put to use, such as turfing or finishing the shoulder of a road or runway, it should be wasted along the edges of the project, as shown in figure 15-64. Take care not to disturb necessary drainage. Equipment,  commonly  used  in  stripping,  consists of  a  dozer,  a  scraper,  and  a  grader.  As  mentioned earlier,   the   dozer   is   the   most   often   used   when removing  trees.  Dozers  can  handle  all  short-haul excavations   (up   to   300   feet).   For   long-haul excavations (over 300 feet), scrapers should be used. A scraper may be used also on fine soils for shallow stripping. A grader is used mainly for shaping and finishing a stripped surface. It is adaptable also for ditching,  for  sidecasting,  and  for  sloping  banks. DRAINAGE Drainage is  the  construction  of  facilities  needed to allow excess surface and subsurface water to flow from  the  construction  site.  Properly  designed  and constructed  drainage  systems  are  one  of  the  most important  parts  of  a  construction  project.  Without proper drainage, rainwater and water running off the surrounding ground could turn the area into a lake. It is also necessary to drain off surface water that would soak down and wet the subgrade. The elements, determining drainage needs for a road or project site, are the amount of annual rainfall in the area and the routes or areas that can be used to collect  or  channel  excess  surface  and  subsurface water, such as lakes, ponds, streams, or voids (i.e., gullies). The  type  of  soil  is  critical  to  the  design  and construction of a road. It is poor judgment to construct a road over or through clay, sand, or other undesirable material if it cannot be properly compacted. It is best to bypass this type of material. If a road surface is to endure continued use for years, it must have firm support from the subgrade. All organic   materials,   such  as  living  or  decayed vegetation, should be removed from the area of the subgrade  unless  the  road  is  for  emergencies  or  is temporary (detour or military road). In designing and building  a  road,  consider  the  type  of  drainage,  the  type of  soil,  and  the  amount  of  clearing  or  grubbing necessary. To  facilitate  drainage,  excavate  diversion  ditches to  conduct  all  surface  water  into  natural  channels  or outfall ditches.  Outfall ditches  are constructed to drain low or boggy spots. At the point or the end of the system when the accumulated runoff discharges into the disposal point, the runoff is technically known as discharge.  The discharge point in the system is called the outfall. This preliminary work is done at the same time the area is cleared and grubbed. The finished drainage system usually consists of ground slopes, ditches, culverts, gutters, storm drains, and underground water drains. Open channels should Figure15-64.-Stripping. 15-40







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