4) Ditching (1-2 km/day) 



a) Equipment entry - dragline or clamshell dredge 

 with runners or pads for moving across soft soil, 

 marsh buggy with backhoe 



b) Equipment digs a ditch 1-2 m deep, 2-3 m wide 



c) Spoil is stacked in continuous pile next to ditch 



d) Equipment exits at end of line, returns along 

 original path, or remains to backfill ditch 



5; Pipe welding and pushing (all done from barge) - all 

 activities IV.A.l.a.6 to IV. A. 1. a. 8 done at stations 

 on push barge (0.25-1.5 km/day) 



a) Pipe positioned on line and welded (several welds) 



b) Welds are cleaned and series of coatings put on 

 pipe 



c) Each new section pushed off end of barge, floats 

 added 



d) A marsh buggy with boom is used to steer anterior 

 end of pipe string (capped) - may push 11-24 km 

 of pipe before sinking it or repositioning push 

 barge 



e) Floats are released from pipe which sinks in ditch 



f) Floats are rafted along push canal and hauled 

 back to push barge - buggy may return to barge 



g) Dragline or buggy mounted backhoe backfills the 

 ditch 



h) Ditching or filling equipment exists or returns 



6) Barge removed from site (1-2 days) 



a) All equipment placed on barges 



b) Barges removed from area by tug 



c) Canal and push slip may be plugged - see steps 

 II.F.a.b.3 



7) Cathode device placement - see steps IV.A.l.a.13 

 c. Completely waterlogged marsh soils - Flotation method 



1) Survey canal - see steps IV.A.l.b.l (1-5 km/day) 



2) Dredge entrance to marsh - see steps IV.A.l.b.2 (1-2 

 days ) 



3) Dredge canal (200-300 m/day) 



a) Draglines dredge canal 12-15 m wide, 2-3 m deep 



b) A deeper area of canal 3-4 m may be dug for the 

 pipe itself 



c) When crossing other pipelines a suction dredge 

 is used to dig under other line 



d) Spoil is heaped in piles or piles withbreaks on 

 both sides of canal, with 9-12 m berm - piles 

 1-2 m high, 15-26 m wide 



4) Pipeline fabrication and lowering into ditch - all 

 activities IV.A.l.a.6 to IV.A.l.a.8 done at stations 

 on lay barge (0.25-1.5 km/day) 



a) Lay barge positioned in canal by tugs, spuds, 

 anchors - note: usually barge-mounted crew 

 quarters nearby. 



b) Pipe positioned on line and welded (several welds) 



c) Welds are cleaned and series of coatings put on 

 pipe 



435 



