Utility Conflict and Soft Fill at a Tight Pile Line
Your crew is preparing to drive 45-ft, 14-in square prestressed concrete piles for a bridge abutment with a diesel hammer and fixed leads. The site is a tight, recently placed engineered fill pad beside an open two-lane road. Utility locate marks show an 8-in water main crossing the proposed pile line near station 12+40, but the marks end about 15 ft from the pile row. The access route crosses a soft area where a loaded concrete truck recently rutted the fill. The foreman wants to start at the pile nearest the road because the crane is already positioned there. The daily briefing has not been held, and the signalperson has not walked the pile line. Before any pile is picked or leads are raised, you must decide what site conditions to verify and how to sequence the work without damaging the main or creating a stability problem.
1. What job-specific checks should be completed before the crane or leads move onto the fill?
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Treat the move as a planned lift and a site-access decision, not a routine reposition. Walk the route and pile line with the signalperson; confirm the utility locate ticket is current, marks are visible, and the water main's actual alignment and depth are known-not inferred from marks that stop 15 ft away. Check the fill's compaction and bearing under each track or outrigger with the competent person; a rutted access route is evidence the fill may not support the crane. Verify the crane is level, mats are sized for the ground, the swing path and exclusion zone are clear, the daily briefing covers the utility and soft-ground hazards, and the operator has the load chart. If any item is unresolved, do not raise leads; relocate the setup or get engineering direction.
2. The marks stop 15 ft from the pile row, but the main is shown crossing at 12+40. How should the crew resolve the conflict before driving?
Read the worked answer
Stop the sequence at that pile. The marks stopping 15 ft short do not prove the main is clear of the pile row; the crossing station and the pile line must be reconciled by a positive locate. Have the utility owner or an authorized locator pothole by vacuum or soft dig at the crossing and mark the actual pipe edges and depth. Keep the required clearance from the outside of the pipe to the pile, and do not drive until the engineer or utility representative confirms the pile location is acceptable. If clearance cannot be met, relocate the pile or revise the foundation with engineering approval. Record the locate, the clearance, and the decision in the daily record, and brief the operator and signalperson before anyone raises leads.
3. How should the soft access area change the planned start point and crane setup?
Read the worked answer
Move the start point away from the rutted fill. The rutting shows the access route has already failed under a loaded truck, so a crane with leads is not a routine move. Have the competent person evaluate bearing and compaction, then place engineered mats or a crane pad sized for the track or outrigger loads, keep the crane level, and keep the boom and lead swing path over stable ground. If the fill cannot be verified, do not position there; use an alternate setup and a longer reach only after checking the load chart. Travel with the leads lowered and no pile suspended. Monitor for settlement during the shift, and stop if the mats pump or the crane goes out of level.