Reproduced from the holdings of the National Archives Pacific Southwest Region #239 DLN Irevs 8 o28 53 and the azimuth of the line. The correction is then applied to the elevation of each bench mark and the resulting elevation isthe height above a datum plane perpendicular to the radius of curvature and pass-= ing through the vertical axis of the working points at either end of the line, Grades and elevations, based on this datum, have been competed for each pipe line. Stations 1220 and 2230 The procedures to establish vertical and horizontal control for these stations should be generally the same as for Station 1203 but can be modified somewhat due to the shorter lines. Three intermediate points are recommended for Station 2220 and two for Station 2230, Due to the greatly reduced overall distance at Station 2230 the transit with double vertical hairs, which is available at the jobsite, should be satisfactory for the alignment operes ations. Pipe Line Alignment Procedure Alignment of the individual pipes requires two operations, Vertical alignment and horizontal alignment. Due to the large number of adjustments to be accomplished the time and man power required to make an individual adjustment must be held to a minimum. The following procedure is submitted as a basic method subject to modification and improvement resulting from experience gained during the progress of the work. This method provides for establishing basic controls on the pipe supports from which the actual + adjustments can be made with a minimum of support from survey personnel. The first step is to bring the pipes into vertical alignment followed by the horizontal alignment and permits completing all adjustments at a support before moving to the next support. Vertical Alignment This adjustment is made by relation to a reference piane established on each set of pipe support posts (See Sketch No. 2). To simplify the computations it may be practical to establish’ a group of these reference planes at the same elevation. For example, elevation 13.00 from station 0 + 27.3 to station 30 + 00 and elevation 10.00 from station 30 + 00 to station 7 + 60.75. (1) A level circuit is run on each side of the array checking through all bench marks. A ‘spike fs set in the face of the outer posts, on the opposite side trom the cross beams, to the elevations as suggested above. The spike must be stable and provide an accurate surface for support of the reference beam. (2) A wire is stretched taut between the two spikes at a pipe support and spikes set on this line in the intermediate posts. This will provide a line of spikes at each pipe support all at the same elevation, (3) A length of standard 3" structral aluminum I beam is laid across a pair of spikes providing a reference plane of known elevation.