Storm sewer takeoff: pipe runs, structures and depth-based counts

Storm sewer takeoff looks simple on the plan view — lines between circles — and gets complicated the moment you price it. The same 400 LF of pipe costs wildly different amounts at 4' of cover versus 16', in rock versus sand, inside a road box versus in an open field. A takeoff that captures only footage has thrown away most of the information the estimator needs.

Set up conditions before you trace a single run

Storm pipe should be split by everything that changes its price. At minimum that means size and material; on many jobs it also means class, joint type and bedding.

Measure pipe along the centerline, consistently

Trace each run from structure center to structure center. Whether you deduct structure diameters is less important than doing the same thing every time and saying so — most estimators measure center to center and let the small overage cover cutting waste and connection work.

• Follow the pipe alignment, including bends; do not shortcut a curved run with a straight line.
• Use the plan view for horizontal length, the profile for depth and slope.
• Split a run wherever size, material or cover band changes — that split is what makes the numbers usable.
• Include stub-outs, roof drain leads and yard drain laterals as their own conditions.

Count structures the way they are bought

Structures are counted, but the count is only useful when it carries type and depth. Rim minus invert from the profile or the structure table gives you depth; sort that into the bands your supplier quotes.

1. Build the structure list from the structure table if the plans include one.
2. Verify each structure appears in the plan view — tables go stale after addenda.
3. Compute depth as rim elevation minus lowest invert.
4. Assign to a depth band and count within type: inlets, catch basins, manholes, junction boxes, end sections.
5. Add castings, frames, grates and hoods as separate line items if bid separately.

Flared end sections, headwalls, riprap aprons and trash racks are easy to miss because they sit at the ends of runs, often outside the main plan-view area. Sweep the outfalls specifically.

Use the profile to price the trench, not just the pipe

Depth drives trench excavation, bedding, backfill, shoring, dewatering and restoration. Reading the profile lets you assign each pipe segment to a cover band and pick up the details that never appear in plan view: crossings with water and sanitary, utility conflicts, rock lines, and existing lines being crossed.

Related quantities that hang off the pipe

• Trench excavation and backfill — often derived from LF, depth band and trench width.
• Pipe bedding stone — LF times section area, converted to tons.
• Pavement cut, patch and restoration where runs cross drives and roads.
• Connection to existing structures — usually priced each, and usually shown only in a note.
• Testing, televising and as-built survey, if the specification requires them.

Reconcile against the engineer's table

Most storm plans include a quantity summary. Compare it to your totals by size. Small differences are normal — rounding, different deduction conventions. Large differences usually point to a missed run on a match line, a sheet at a different scale, or a portion of the system shown only on an off-site or utility sheet. Chasing those differences before pricing is far cheaper than discovering them after award.