For an aboveground utility, such as a pole mounted telephone, telegraph, or power line, the survey problem consists simply of locating the line horizontally as required and marking the stations where poles or towers are to be erected. Often, the directions of guys and anchors maybe staked as well, and sometimes pole height for vertical clearance of obstructions is determined.

For an underground utility, you will often need to determine both line and grade. For pressure lines, such as water lines, it is usually necessary to stake out only the line, since the only grade requirement is that the prescribed depth of soil cover be maintained. However, staking elevations may be necessary for any pressure lines being installed in an area that (1) is to be graded downward or (2) is to have other, conflicting underground utilities.

Gravity flow lines, such as storm sewer lines, require staking for grade to be sure the pipe is installed at the design elevation and at the gradient (slope) the design requires for gravity flow through the pipe.

Grade for an underground sewer pipe is given in terms of the elevation of the invert. The INVERT of the pipe is the elevation of the lowest

Figure 14-41.-Use of batter boards (with battens) for utility shakeout.

part of the inner surface of the pipe. Figure 14-41 shows a common method of staking out an underground pipe. Notice that both alignment and elevation are facilitated by a line of batter boards and battens (small pieces of wood) set at about 25- to 50-ft intervals. The battens, nailed to the batter boards, determine the horizontal alignment of the pipe when placed vertically on the same side of the batter boards and with the same edges directly over the center line of the pipe. As the work progresses, you should check the alignment of these battens frequently. A sighting cord, stretched parallel to the center line of the pipe at a uniform distance above the invert grade, is used to transfer line and grade into the trench. The center line of the pipe, therefore, will be directly below the cord, and the sewer invert grade will be at the selected distance below the cord. A MEASURING stick, also called a grade pole, is normally used to transfer the grade from the sighting cord to the pipe (fig. 14-41). The grade pole, with markings of feet and inches, is placed on the invert of the pipe and held plumbed. The pipe is then lowered into the trench until the mark on the grade pole is on a horizontal line with the cord. 

Figure 14-42 shows another method of staking out an underground sewer pipe without the use of battens. Nails are driven directly into the tops of the batter boards so that a string stretched tightly between them will define the pipe center line. The string or cord can be kept taut by wrapping it around the nails and hanging a weight

Figure 14-42.-Batter boards (without battens) for utility stakeout.

on each end. Similarly, the string (or cord) gives both line and grade.

A finished structure seldom corresponds exactly to the original plans in every detail. Unexpected, usually unforeseeable difficulties often make variations from the plans necessary or, occasionally, variations may occur accidentally that are economically unfeasible to correct.

The purpose of an AS-BUILT SURVEY is to record these variations. The as-built survey should begin as soon as it becomes feasiblemeaning that the actual horizontal and vertical locations of features in the completed structure should be determined as soon as the features are erected. At times, variations from the original plans are recorded on new tracings of the working drawings, on which as-built data are recorded in the place of the original design data when the two happen to differ. Sometimes, reproductions of the original drawings are used with variations recorded by crossing out the original design data and writing in the as-built data.