Pipe only works if the water runs downhill the whole way. This cut sheet tracks each run structure-to-structure — pipe size, material, design slope, then station-by-station design invert versus actual invert with grade rod and cut so the pipe crew always knows where the flowline belongs.
Or skip the spreadsheet
Gradelog tracks pipe runs, structures, and invert acceptance digitally — with slope math done for you and as-built exports the engineer will actually accept.
The invert is the lowest interior point of a pipe — the flowline the water actually follows. Invert elevations, not top-of-pipe, are what plans specify and inspectors check, because gravity systems live and die by flowline elevation. Design inverts at each structure define the slope the run must hold between them.
Common gravity-sanitary minimums are 2.0% for 4-inch, 1.0% for 6-inch, and 0.40% for 8-inch pipe, tapering down for larger diameters — values derived from maintaining 2 ft/s cleansing velocity. Storm systems can run flatter. Local code and the project plans always govern; some jurisdictions require more than the textbook minimum.
Slope equals the invert elevation difference divided by the horizontal distance, times 100 for percent. If the upstream invert is 101.50 and the downstream is 100.30 over 240 feet, the slope is (101.50 − 100.30) / 240 = 0.50%. Compute it from the plan inverts and verify it matches the slope printed on the profile — discrepancies are RFI material.
The laser holds grade between setups, but setups get bumped, bedding settles, and pipe gets pushed during backfill. A shot log at each joint catches drift while the trench is still open — fixing a low joint costs minutes then, and days after paving. The completed log is also your as-built evidence when the camera inspection questions a belly.