Storm drain as-built documentation is the record that gets the city to sign off on infrastructure acceptance — and the record that protects the contractor when a flat spot or slope reversal is discovered at final inspection years later. The documentation must be produced during installation, not after backfill, when the only way to verify inverts is to excavate.
What documentation does a city require for storm drain installation acceptance?
City engineers typically require the following storm drain documentation for system acceptance: as-built invert elevations at all inlets, outlets, manholes, and junction structures; pipe size, material, and class for each run; installed slope for each pipe run calculated from actual invert data; manhole rim elevations and structure GPS coordinates; depth of cover at representative points; pipe material certification; any deviation from design approved by the city engineer; and a system schematic or annotated plan showing the as-built data. Documentation must be produced before backfill conceals the system.
| Structure Type | Required As-Built Data |
|---|---|
| Manhole | Rim elevation; all pipe inverts (in and out) by size and direction; structure GPS coordinates; manhole type and size |
| Inlet / catch basin | Grate or throat elevation; outlet pipe invert; structure GPS coordinates; inlet type |
| Outlet structure | Outlet invert; wingwall or headwall dimensions; energy dissipation type if applicable; GPS coordinates |
| Pipe run (between structures) | Pipe size, material, class; upstream and downstream invert elevations; actual slope calculated from inverts; length; joint type |
| Junction box | Rim elevation; all entering and exiting pipe inverts; GPS coordinates; box dimensions |
Pipe slope verification during installation is more reliable and less expensive than discovering a slope reversal after backfill. The two methods used in the field:
For large-diameter culverts or box culverts, survey control is typically used — a total station or GPS rover establishes the pipe invert elevation at each end of each section before placement. These measurements become the as-built record with no additional step required.
| Rejection Reason | Prevention |
|---|---|
| Missing invert data at one or more structures | Survey every structure before backfill — not just the main line manholes |
| Calculated slope does not match design (by more than tolerance) | Check slope from invert data during installation; correct before backfill |
| Slope reversal on one or more runs | Use pipe laser to catch grade errors as each section is placed |
| Pipe material or class not documented | Record pipe material from delivery tickets; keep ASTM or AASHTO certification on file |
| GPS coordinates missing or inaccurate | Use GPS rover to collect structure coordinates; verify against design coordinates |
| Deviation from design not approved | Any as-built invert more than tolerance from design requires a written approval from the city engineer before submission |
The city acceptance package for storm drain typically includes:
Sitemark captures storm drain invert elevations and structure data in real time during installation and generates the city acceptance package — annotated schematic, tabular schedule, and GPS coordinate list — without requiring a separate office data entry step.
Sitemark captures invert elevations and structure data during installation and generates the city acceptance package automatically. Submit documentation to the city engineer before the backfill crew is off site.
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