The first step in site grading is to know your topography and where water flows on or off during and after rain. Prior to any earthwork, any low spots, slopes that will drain to structures, and areas where the prior grading has settled out of level are identified as problem areas. Rough grading sets the elevation and overall drainage pattern of the site. This is the stage where significant material is moved: cutting down high areas and building up low ones to establish the basic shape that the finished site will follow. Equipment selection depends on the scale of the site and the access available, with compact machinery suited to established residential properties where surrounding landscaping needs to be protected, and larger equipment appropriate for open commercial and rural sites. Finish grading refines the rough grade to the precise tolerances that concrete installation and final landscaping require. The transition between graded soil and finished concrete edges, the slope across areas that will remain as lawn or landscaping, and the final surface profile around drainage points are all established during finish grading. This is a more critical and deliberate procedure than rough grading since the accuracy here will have an impact on the performance of all of the surfaces that follow. Grading for drainage correction on existing properties deals with issues that have arisen over time: soil that has settled over time, creating lower areas where it was not intended; landscaping changes that have altered the way water moves across the property; and construction or improvement infrastructure that has impacted on the original flow of water across the property. The solution to these problems is to modify the impacted region to restore drainage conditions.