Download
StormSewer is a free, open-source desktop program for gravity storm-drain design and analysis. Draw the network on a scaled aerial or import it from a Hydraflow / Civil 3D Storm Sewers .stm file, LandXML or DXF, then run the Rational method, Manning capacity for circular, box, elliptical and arch conduits, and a standard-step HGL/EGL backwater pass with junction losses and tailwater. HEC-22 inlet interception carries bypass from one inlet to the next.
Reports come out as a submittal PDF with a title block on every page, ruled pipe, structure and inlet schedules, a scaled plan, and a profile with real elevation and station axes. HTML, CSV, LandXML and DXF export too.
The methods are public domain and the implementation is readable. Every number is worked by hand in VALIDATION.md, and the same network was run through Autodesk Hydraflow Storm Sewers, every difference explained. Compared, not certified.
Windows, macOS, Linux. Written by a practicing water resources PE. GPL-3.0.
Features
- Rational method flow accumulation down a dendritic network
- Manning partial-flow hydraulics: circular, box, elliptical, arch
- Standard-step HGL and EGL with junction losses and tailwater
- HEC-22 inlet interception (grate, curb, combination, sag) with bypass carryover
- Auto-sizing to velocity and percent-full criteria
- Tc by Kirpich, TR-55 sheet flow or FAA, accumulated pipe by pipe
- NOAA Atlas 14 import with IDF fitting
- Imports Hydraflow / Civil 3D .stm, LandXML and DXF
- Exports submittal PDF, HTML, CSV, LandXML and DXF
- Design review: cover, freeboard, velocity, surcharge, adverse slopes
