benchmark reduced level= 1267.841 m
staff reading at benchmark=0.310 m
staff reading at 3 ground levels X,Y and Z: X=1.327 m, Y=1.214 m and Z=1.607m
invert level at X=1265.248 m . the gradient from X to Y is 1 in 80 for a distance of 40 m and the gradient from Y to Z is 1 in 100 for a distance of 60 m. the boning rod is 3 m.
a. what was the depth of each manhole?
b. what was the height of the sight rails above the ground at X, Y and Z?