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Back-Fill Calculations
CALCULATING BACK-FILL FOR A SLOPE (REQUIRES KNOWN PERCENT GRADE)
Example: A retaining wall is being constructed at the base of a hillside that a path is being built along.
The length of wall is to be 50 Feet and the height will be 4 Feet 6 Inches. You need to ll in the space
up to 2 Inches from the top of the wall. The percent grade of the hill is 60% How much ll do you need?
This can be solved for by treating the ll space like a right triangle equation.
Remember to press to clear entries in between problems.
On/C On/C
KEY INPUT & DISPLAY
%GRD 60
2. Find the Run of the triangular space that the ll will occupy.
RUN 7
Feet
2-11/16
Inch
50
Feet
3. Find volume of ll required as if it was a rectangular space:
RUN 5
Feet
0
Inch
1564.815
CU Feet
782.4074
CU Feet
0
1. Solve for the Rise of the triangular space.
4
Feet
4
Inch
RISE 4
Feet
4
Inch
3. Divide in half to nd volume of a right trianlge space:
Pitch
Run
%
0
Feet
5
0
×
RunRcl
÷
2
=
6
Rise
Inch
4
On/C On/C
Feet
–
2
Inch
=
6
Inch
4
Feet
4
Inch
4
Feet
4
×
2”
(?) Rise
(?) Run
60%
Grade
4’ 6”
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