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 areference line 10 feet from the center line of a bridge.Stretch a wire rope between points A and B with a pieceof tape or a wire rope clip at each pile-bent position(such as C or D).Locate the upstream pile (pile No. 1) by measuringan offset of 4 feet from the line AB at C. A template isthen floated into position and nailed to pile No. 1 afterit is driven. The rest of the piles are positioned by thetemplate.If it is impractical to stretch a wire rope to the farshore, set up a transit at a convenient distance from thecenter line of the bridge. Position the piles by sightingon a mark located the same distance from the center lineof the template. Before driving piles, you must measurethe length of piles. Measure the distance between thepiles by chaining.During pile driving, keep a complete record of thefollowing: location and number of piles, dimensions,kind of woods, total penetration, average drop ofhammer, average penetration under last five blows,penetration under last blow, and amount of cutoff.Mark elevations on the two end piles by nailing two3- by 12-inch planks to guide the saw in cutting thepiles to the specified height.BRIDGE GRADE STAKES.— Elevations aretaken from bench marks set in, or near, theFigure 10-18.—Method of positioning piles.construction area. Consider permanency, accessibil-ity, and convenience when setting bench marks. Setgrade stakes for a bridge site in the same manner asthe grade stakes on any route survey. Make sure thatthe senior petty officer in charge of the job has suf-ficient information so that the exact method beingused to designate the grade can be understood.Sewer StakeoutTo stake out a sewer, you obtain data from a planand profile that shows (1) the horizontal location of eachline in the system, (2) the horizontal location and char-acter of each manhole, (3) the invert elevations at eachmanhole, and (4) the gradient of each line. You will alsohave detail drawings of each type of appurtenance. Ifmanholes in the same category are of different types,you may identify them by letter symbol, as CI “A,” andso 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 tomark the alignment and indicate the depth of the sewer.The alignment may be marked by a row of offset hubsand stakes or by both offset hubs and a row of center-line stakes. Cuts may be shown on cut sheets (also calledgrade sheets or construction sheets) or may be markedon the stakes, or both. The cuts shown on the center-linestakes 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 tothe bottom of the trench, taking into account the depthto the invert, the barrel thickness, and the depth of anysand or gravel bed. The cuts marked on the stakes nextto the hubs are generally shown to hundredths andusually represent the distance from the top of the hub tothe invert; these cuts guide the pipe crew. The use ofthese cuts in transferring the information to batterboards 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, thenthe construction crew usually sets center-line stakes forline only and uses the hubs as a guide for the depth ofexcavation. 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 crewdepend on the capabilities and the availability of per-sonnel and the work load. In any case, hubs and/orstakes are generally set at 25-foot intervals, though50-foot and even 100-foot intervals have been knownto suffice.Sewer hubs are usually offset from 5 to 8 feet fromthe center line. Before you enter the field, youcompute from the profile the invert elevation at every10-19
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