Storm and Sanitary Analysis alternative for detention ponds
For an engineer who sizes site detention in Autodesk Storm and Sanitary Analysis (SSA): what Autodesk says about its future, the method basis PondSheet shares with it, and what PondSheet leaves out.
What Autodesk says about SSA
Autodesk calls SSA a legacy application it is transitioning away from and plans to retire. It is no longer downloaded automatically with current Civil 3D releases, and Autodesk has not announced the retirement date. For the core drainage work done in SSA, Autodesk names the drainage tools in Civil 3D as the path forward, with InfoDrainage licensed separately (Autodesk: What’s happening with SSA).
What is the same
The pond work rests on the NRCS method in both. Autodesk’s brochure for the SSA extension lists its hydrology methods and pond analysis; the rows below quote it.
| Method | Storm and Sanitary Analysis | PondSheet | Basis |
|---|---|---|---|
| Runoff | NRCS (SCS) TR-55/TR-20, among its hydrology methodsAutodesk: Storm and Sanitary Analysis brochure | TR-55 runoff with the NRCS dimensionless unit hydrograph | TR-55; NEH 630.16 |
| Rational method | Rational and Modified Rational, among its hydrology methodsAutodesk: Storm and Sanitary Analysis brochure | Rational method as a drainage area’s method; the modified rational critical-duration estimate in the detention volume calculator | FHWA HEC-22; NYC DEP |
| Ponds | Analysis and design of detention and retention pondsAutodesk: Storm and Sanitary Analysis brochure | Detention ponds and chamber systems, by storage-indication routing | NEH 630.17 |
| EPA SWMM | EPA SWMM, among its hydrology methodsAutodesk: Storm and Sanitary Analysis brochure | A SWMM 5 input file per storm with every report, which EPA SWMM opens and re-runs | EPA SWMM 5 |
What differs
PondSheet runs in the browser, on every edit, for $99 per firm per month, unlimited engineers and projects. It needs no Civil 3D seat.
- Civil 3D stage-storage
- Copy the stage-storage table from a Civil 3D report and paste it into the pond’s first cell. A header row is dropped, computed columns are skipped, and one sentence says what was pasted.
- Reviewer link
- A read-only link for the plan reviewer, with the report, the SWMM .inp and the model file. The reviewer needs no account.
- SWMM 5 input
- Every report comes with a SWMM 5 .inp per storm: the pond’s stage-storage, its outlets and the inflow hydrographs, to open and re-run in EPA SWMM.
- Frozen site data
- NOAA Atlas 14 depths and the USDA soil survey are fetched by the server for the site and frozen with the project. An update is the engineer’s choice, and it is logged.
- Check sets
- The criteria are the engineer’s: peak control, WQv, drawdown, freeboard, the emergency spillway, the smallest orifice, each with the source the engineer cites. The NYSDEC manual ships as a built-in template.
What PondSheet does not do
PondSheet sizes ponds and chamber systems for a site. The brochure lists pipes, open channels, culverts, inlets and sanitary systems for SSA (Autodesk: Storm and Sanitary Analysis brochure); PondSheet does none of that drainage work.
- Storm sewer networks
- No pipe networks, inlets or catch basins.
- Culverts
- No culvert design. A pond’s barrel through the berm is its outlet.
- Channels
- No channel routing. A channel appears only as a Tc segment.
- Sanitary sewers
- Not modeled.
- CAD and grading
- The site map locates the project; it is not a drawing, and nothing is read from a Civil 3D surface. Stage-storage comes in as a pasted table.
- 2D flood modeling
- No 2D flood modeling or large-watershed studies.
The equations, with their pages, are on the methods table; how the engine is checked against published examples and EPA SWMM is on the validation page. The free calculators run the same engine with no account.
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Autodesk and Civil 3D are registered trademarks or trademarks of Autodesk, Inc.; Storm and Sanitary Analysis and InfoDrainage are Autodesk products. PondSheet is not affiliated with Autodesk.