Sanitary sewer takeoff from plan and profile sheets

Sanitary sewer is gravity work, and gravity means depth. A run that starts at 5' of cover and ends at 18' has the same footage on the plan view and several times the installed cost. A sanitary takeoff that ignores the profile is not a takeoff — it is a length measurement.

Build the conditions from the way it is installed

Work the plan view and the profile together

1. Calibrate the plan sheet, then trace each run manhole center to manhole center for horizontal length.
2. Open the profile for the same stationing and read rim and invert elevations at each structure.
3. Compute cover at both ends of the run and assign the run to a depth band; split the run where it crosses a band.
4. Note the slope — flat runs invite dewatering and bedding issues that belong in the price.
5. Mark utility crossings shown on the profile; each one is a potential conflict item.

When cover changes a lot within one run, split it into two or three segments rather than averaging. Averaging hides the expensive half.

Counted items estimators routinely miss

• Service laterals, including the wye or tee, riser and cleanout at the right-of-way line.
• Connections to existing manholes — cored, boot-sealed, and often priced each.
• Doghouse manholes and inside drops shown only in a detail.
• Bypass pumping for tie-ins to a live system, usually specified in the notes.
• Testing: air test, mandrel test, vacuum test on manholes, and televising.
• Abandonment items: plugging, grouting or removing existing lines.

Force main is a different animal

If the project includes a pump station and force main, keep those quantities entirely separate. Force main is pressure pipe: it follows grade rather than slope, uses restrained joints and fittings, needs air release valves at high points, and is tested by pressure rather than by mandrel. Mixing it into the gravity conditions produces a total nobody can bid from.

Quantities that follow from the pipe

• Trench excavation by depth band, with rock allowance if the geotech indicates it.
• Bedding and pipe zone stone, converted from LF to tons using the trench section.
• Select backfill versus native backfill, especially under pavement.
• Pavement removal and replacement where runs cross streets and drives.
• Surface restoration: topsoil, seed, sod, or full pavement section.

Final reconciliation

Sum your footage by size and compare it to the engineer's summary and to the manhole-to-manhole table if one is provided. Then check the structure count against the profile — every profile break should have a structure, and every structure should be counted once. Two sheets sharing a manhole at a match line is the most common source of a duplicated structure and a duplicated run.