(a) Line and grade stakes shall be set on the natural ground surface. Three batter boards, a top line and grade pole shall be used to transfer the line and grade to the bottom of the ditch, unless some other method of checking the inner lower grade and line is approved by the Engineer in writing. The contractor must test the ditch or grade of the top line and sewer and will be held responsible for the correct flow of sewers. In every case, the contractor must install on the batter lines an accurate line level to test the downward grade of the pipe in the direction of flow.
(b) The contractor shall provide and maintain on the work at all times a gauge rod of sufficient length of reach from the invert of the sewer pipe being laid to the top line strung on the three batter boards. The gauge rod shall be graduated and numbered each foot of its entire length. The gauge rod shall be equipped with either a plumb line or two spirit levels, and the utmost care must be used to insure a truly vertical gauge rod at the time the reading is taken and the pipe is being set.
(Ord. 352. Passed 10-22-62.)