landscape Grading

basic,process,importance,principle,gradient etc

1. GRADING BASICS Grading is the process of modification of existing landform to accommodate new structures, parking and circulation and to ensure positive drainage. Consideration must be given to utilities such as: water, gas, power, communication services, and sewerage for disposal of wastewater, and storm water. Grading process requires a careful change of contours so that they support the integration of building with the site .

2. The land m ay be graded or adjusted to suit the architectural or engineering requirements, or the architecture may be adopted to meet variations in the ground level so that the original surface is disturbed the least. Extensive alterations in the landform may lead to unstable conditions resulting in erosion, landslides, floods, and a complete destruction of ecosystem. IMPORTANCE OF GRADING

3. The ground surface must be suitable for the intended purpose or use. The visual result should be pleasing. The result of any grading must have positive drainage. The grading plans should attempt to keep new levels as close as possible to the original state of the land. When ground is reshaped it should be done positively and at the scale of the machinery. Top soil must be conserved wherever possible. The quantity of cut should be approximately equal to the quantity of the fill. PRINCIPLES OF GRADING TECHNOLOGY

4. Three principal goals in development of a grading plan are: Keep unwanted water from entering a building. Keep surface run off from creating damage to property or people during periods of heavy rainfall and subsequent runoff. To accommodate the structure on site with disturbing the site to minimum.

5. GRADIENT Gradient refers to the changing elevation along the Earth's surface or the rate of the slope. It is expressed in % or ratio or degrees. 1% slope = 100:1 10% slope = 10:1 = Percentage of slope is expressed as the number of meters (feet) rise in 100 m (100 ft) of horizontal distance, typically referred to as rise/run. If the slope rises2 m (2 ft) in 100 m (100 ft), it is considered a 2 percent slope. The percentage of slope can be calculated by the following formula: Where D=vertical rise, mm (ft) L=horizontal distance, mm (ft) G = gradient, %

6. Elevation of point B=48 347 mm Elevation of point A =47 463 mm Vertical difference D= 884 mm Horizontal difference L= 35 357 mm There fore:

7. SPOT ELEVATIONS Spot elevations provide additional information beyond that given by the contour lines. They indicate Micro grading. Spot elevations are used to establish limits of slope, to locate contour lines, and to provide detail for establishing control points that cannot be obtained via contour lines. Typical locations for taking spot elevations are: Top and bottom of steps. Tops of retaining wall. Outside entrances to buildings. Inside floor levels of buildings. Corners of all structures.

8. GRADING FOR DEFINED AREA Slopes of less than about 2 percent in the open landscape appear flat to the human eye. However, in areas adjacent to built structures, even the slightest slope becomes noticeable because of the relationship of the grade to mortar joints, roof lines and other level architectural features.

9. Perimeter Edge Level: Figures schematically illustrate alternative methods for manipulating a surface for drainage while allowing at least one peripheral edge to remain level.

10. Entire Area Level: Some circumstances, such as rooftop landscapes or enclosed courtyards, require that the entire surface of the enclosed area be level. Figure ahead illustrates two ways that an area can remain level and still drain properly by the use of porous surface material, such as sand/gravel the use of individually elevated Each case requires an adequate system beneath the pavers to carry required rainfall effectively.

11. These alternatives are applicable to relatively flat surfaces as tennis courts and other types of courts.

12. SCHEMATIC GRADING FOR OPEN AREAS Preparing site grading plan Grading of a site should be thoughtful systematic process that begins with an analysis and understanding of the site and ends with an overall detailed Grading plan. Site Analysis: Study the general lay of the land by using topographic maps and site visits. 1. Determine high points, low points, ridges, and valleys. 2. Note natural drainage systems and directions of flow that exist on the site. Site use concept: Determine how existing landforms would affect proposed use areas, such as building locations, roads, parking areas, walkways, plazas, and lawn areas.

13. SITE ANALYSIS (EXAMPLE)

14. CUT AND FILL The process of removal of earth from one part of site to achieve required grading and the place and using the dug up earth to achieve required grading by filling it at another place on the same sit. The amount of material from cuts roughly matches the amount of fill needed to make nearby embankments, so minimizing the amount of construction labor.

15. Standards for grading around a typical building.

16. Surface drainage can be achieved by pitching surfaces to natural drainage feature and systems.

17. Grading to create berms . Berms can be created for noise and wind barriers or for additional soil depth above unfavorable sub-grade conditions, such as a high groundwater table.

18. Grading to create level areas. Relatively flat gradients are needed for sports fields, outdoor terraces, and sometimes for areas near buildings.

19. Grading to modify existing landforms. Deep gullies, narrow ridges, or steep slopes can be modified to create more useful and attractive landforms.

20. Grading for increased site interest. Grading can help emphasize a site's topography or add interest to an otherwise flat site.

21. Grading related to good views.

22. Grading to expose vistas

23. Grading related to bad views.

24. Grading to fit structures to sites.

25. Grading to facilitate better plant growth

26. Grading to emphasize or control circulation.

27. RECOMMENED GRADIENTS

28. RECOMMENED GRADIENTS

29. Schematic grading for outdoor basketball court

30. GRADING FOR STREETS AND ROADS The road has a constant slope and thus presents more problem. The function of the road is to serve as an path for vehicles and as an adjunct to the drainage system. A road must be designed: in conformance to strict design standards, maintaining appropriate grades, curvatures and sight distances. To minimize fluctuations across variable terrain. To have a constant slope or gradient. To provide shortest route possible. To minimize cut and fill. As far as possible parallel to the contour lines.