You have a required elevation at “A” of 104.25. The benchmark elevation is 101.10. A back site reading opf 4.65 is taken. A front site at the grade you are checking (location “A”) has a reading of 1.50. What needs to be done?

You have a required elevation at “A” of 104.25. The benchmark elevation is 101.10. A back site reading opf 4.65 is taken. A front site at the grade you are checking (location “A”) has a reading of 1.50. What needs to be done?