Practical Applications; Grade Line For A Sewer; Batter Boards For A Sewer; Stadia Distance Measuring - berger instrument Level and Transit-Level Instruction Manual

11. PRACTICAL APPLICATIONS

11.1. Grade Line for a Sewer

Steps to find the slope necessary for a household sewer connection are shown below
(Fig. 17). Notice that the invert or flow-line of the pipe is used in each instance. The
invert is the bottom of the pipe and this line is the reference from which grades are
commonly given.
Fig. 17
69"

11.2. Batter Boards for a Sewer

Sewers are normally placed at some depth below the surface of the ground, so
batter boards are placed somewhat higher above the invert grade. A typical layout
for sewer batter boards is shown below (Fig.18). The vertical strip nailed to the
horizontal board is set with one edge along the line of the sewer. A nail is placed in
this vertical strip at an even number of feet above the invert. By stretching a taut line
between these nails, the sewer line is easily referenced. A board notched say 8 feet
from its bottom is used to set the pipe.
Fig. 18
14 • Berger Instruments
22"
Cesspool inlet 69"-22"=47" below dwe
Horizontal distance=78'.4 47"=3'.92
Grade of sewer=100x(3.92/78.4)=5%
CUT 2'
A
Detail of grade
stake of A
90°
Driveway grade marked
15'
12'

12. STADIA DISTANCE MEASURING

Distance measurement can be done using the stadia hairs of the reticle.
Read the length " " of a level rod shown between the stadia hairs. The distance to
the target is 100 multiplied by . The distance between point A and point B is L.
On a rod showing inches & eighths, you must convert the inches & eighths to the
decimal form of a foot to get a correct reading. This is done by taking the partial
foot reading, say 7 1/8 inches, and converting by dividing by 12.
= 7.125"/12 = .59 FT.
L = .59 x 100 = 59 FT.
If were 1' 7 1/8" then would equal 1.59 ft. & L = 159 ft.
Offset Grade Stakes for
a 12 foot Driveway
90°
15' 15'
FILL 3'
on stakes
15'
Detail of grade
stake of B
Fig. 19
Upper Stadia Hair
Lower Stadia Hair
L = 100 x
Berger Instruments • 15
B