You need to establish grade to the bottom of a footing that is 1 foot thick with a top elevation of 102.33'. With an existing grade of 106.14' and a backsight of 6.78', what is the correct reading of the rod at the bottom of the footing?

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To determine the correct reading of the rod at the bottom of the footing, we need to calculate the elevation of the bottom of the footing based on the provided information.

The top elevation of the footing is given as 102.33 feet. Since the footing is 1 foot thick, the elevation at the bottom of the footing is calculated by subtracting the thickness of the footing from its top elevation. Therefore:

Bottom elevation of the footing = Top elevation - Thickness

= 102.33 feet - 1 foot

= 101.33 feet

Now, we need to relate this elevation to the instrument's readings. With an existing grade of 106.14 feet and a backsight of 6.78 feet, we will calculate the level of the instrument (the height of the instrument above the existing grade). This is determined by subtracting the backsight reading from the existing grade:

Height of instrument = Existing grade - Backsight

= 106.14 feet - 6.78 feet

= 99.36 feet

Now, we can find the reading of the rod at the bottom of the footing. The rod reading corresponds to the difference between the instrument's height and the elevation at the bottom of the footing

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