Checking Grade with a Level InstrumentAn example of checking ground spots for desiredgrade with a level instrument is shown in figure 15-51.The hubs and stakes at the side of the constructionrepresent offset grade stakes. In figure 15-51, view (A),the grade stake calls for a cut of 7.5 feet. You set up yourlevel and take two readings: first on the hub and then onthe excavation. Your first reading is 5.0 feet. Since theexcavation is supposed to be 7.5 feet below the hub,your second reading should be 12.5 (5.0 plus 7.5 asshown). But the rod reads only 12.2; therefore, you mustcut 0.3 feet more to get to finished subgrade.In figure 15-51, view (B), your first reading is 12.0feet on the hub. Since the stake calls for F 7.0, youshould read 5.0 on the completed fill. But the rod reads5.5; therefore, you must fill another 0.5 feet to finish thesubgrade.MISSING GRADE STAKE.— Another levelingprocedure is to compute a cut-or-fill requirement froma missing grade stake. In figure 15-52, the finish eleva-tion from the project drawings at point B is supposed tobe 378.75. You setup your level, take a backsight shoton the bench mark at point A, and get a direct readingof 11.56 feet. The 11.56 feet backsight reading plus thebench mark elevation of 365.01 feet gives you an in-strument height of 376.57 feet. Then you take a fore-sight shot at point B, and get a direct reading of 1.42feet. You now subtract the foresight reading of 1.42 feetfrom the instrument height of 376.57, and find that theexisting ground is at elevation 375.15. You now takethe required finish elevation of 378.75 and subtract theexisting elevation of 376.15 and get a FILL requirementof 3.6 feet at point B. If the existing elevation is greaterthan the required finish elevation, you would be re-quired to cut.Another example of a missing grade stake is shownin figure 15-53. Suppose the stake at station 4 + 50has been knocked out, and there is no bench markFigure 15-51.—Checking cut and fill.15-30

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