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Figure 10-16.Staking out abutment wing walls. - 14071_218
Sewer  Stakeout - CONTINUED

Engineering Aid 2 - Intermediate Structural engineering guide book
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Piles.—  You may be required to position piles, record  pile-driving  data  and  mark  piles  for  cutoff. Figure 10-18 shows points A and B established as a reference line 10 feet from the center line of a bridge. Stretch a wire rope between points  A and B with a piece of tape or a wire rope clip at each pile-bent position (such as C or D). Locate the upstream pile (pile No. 1) by measuring an offset of 4 feet from the line  AB at C. A template is then floated into position and nailed to pile No. 1 after it is driven. The rest of the piles are positioned by the template. If it is impractical to stretch a wire rope to the far shore, set up a transit at a convenient distance from the center line of the bridge. Position the piles by sighting on a mark located the same distance from the center line of the template. Before driving piles, you must measure the  length  of  piles.  Measure  the  distance  between  the piles by chaining. During pile driving, keep a complete record of the following: location and number of piles, dimensions, kind  of  woods,  total  penetration,  average  drop  of hammer, average penetration under last five blows, penetration under last blow, and amount of cutoff. Mark elevations on the two end piles by nailing two 3- by 12-inch planks to guide the saw in cutting the piles  to  the  specified  height. BRIDGE  GRADE  STAKES.—  Elevations  are taken   from   bench   marks   set   in,   or   near,   the Figure 10-18.—Method of positioning piles. construction area. Consider permanency, accessibil- ity, and convenience when setting bench marks. Set grade stakes for a bridge site in the same manner as the grade stakes on any route survey. Make sure that the senior petty officer in charge of the job has suf- ficient  information  so  that  the  exact  method  being used to designate the grade can be understood. Sewer  Stakeout To stake out a sewer, you obtain data from a plan and profile that shows (1) the horizontal location of each line in the system, (2) the horizontal location and char- acter of each manhole, (3) the invert elevations at each manhole, and (4) the gradient of each line. You will also have  detail  drawings  of  each  type  of  appurtenance.  If manholes  in  the  same  category  are  of  different  types, you may identify them by letter symbol, as CI “A,” and so on. In addition, identification of a particular appur- tenance may be by consecutive number, as CI “A” #3. The stakeout consists of setting hubs and stakes to mark the alignment and indicate the depth of the sewer. The alignment may be marked by a row of offset hubs and stakes or by both offset hubs and a row of center- line stakes. Cuts may be shown on cut sheets (also called grade sheets or construction sheets) or may be marked on the stakes, or both. The cuts shown on the center-line stakes guide the backhoe operator or ditcher operator; they are usually shown to tenths; they generally repre- sent the cut from the surface of the existing ground to the bottom of the trench, taking into account the depth to the invert, the barrel thickness, and the depth of any sand or gravel bed. The cuts marked on the stakes next to the hubs are generally shown to hundredths and usually represent the distance from the top of the hub to the invert; these cuts guide the pipe crew. The use of these cuts in transferring the information to batter boards or various types of offset string lines was de- scribed in chapter 14 of the EA3 TRAMAN. If the survey party stakes only the offset hubs, then the construction crew usually sets center-line stakes for line only and uses the hubs as a guide for the depth of excavation. The extent of the stakeout and computa- tions performed by the survey party and the correspond- ing extent of such work done by the construction crew depend  on  the  capabilities  and  the  availability  of  per- sonnel and the work load. In any case, hubs and/or stakes are generally set at 25-foot intervals, though 50-foot  and  even  100-foot  intervals  have  been  known to  suffice. Sewer hubs are usually offset from 5 to 8 feet from the  center  line.  Before  you  enter  the  field,  you compute from the profile the invert elevation at every 10-19







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