HydroCAD Stormwater Modeling - Since 1986

HydroCAD Supports
Stormwater Storage Products from
Advanced Drainage Systems

HydroCAD provides full support for the stormwater storage products offered by Advanced Drainage Systems, Inc. including N-12 HDPE pipe and StormTech stormwater chambers.

This partnership allows ADS products to be easily used within any HydroCAD model for stormwater storage, detention, or infiltration.  HydroCAD includes complete ADS storage definitions, plus an interactive chamber wizard for easy layout, pricing, and modeling of underground storage systems.

Users of HydroCAD 9.1 and earlier should obtain a program update in order to get the latest chamber definitions.  The HydroCAD-10 update also provides an enhanced chamber wizard with automatic handling of end-caps and pipe headers.

How storage is modeled

Stormwater storage typically appears in a HydroCAD model as part of the storage definition for a "pond".  In the simplest case, HydroCAD calculates the total available storage, including the interior of the chambers, plus the void space in any surrounding stone.  For a more complete analysis, a full stage-storage curve is calculated so that an inflow or runoff hydrograph can be routed through the pond.  The resulting analysis indicates the water levels attained throughout the rainfall event, as well as any discharge that may occur through outlet devices or infiltration into the surrounding ground.

Flexible storage options

Each HydroCAD pond may include an unlimited number of storage definitions as required to describe its overall storage characteristics.  This makes it easy to model complex storage arrangements, such as a combination of multiple chambers, pipe storage, catch basins, or other contributing volumes.

But the most significant feature is the ability to embed (bury) chambers in a bed of stone, and have HydroCAD automatically calculate the combined storage at any water surface elevation.  This makes it easy to determine the storage for virtually any configuration of storage chambers, without resorting to any manual calculations.

Click for complete self-training materialsHydroCAD can also model almost any imaginable storage arrangement, including layered chambers of different sizes combined with auxiliary storage from adjacent pipes and catch basins, and even the above-ground areas (parking lot) that may provide overflow storage for certain events.

Using ADS stormwater products

Setting up a pond to use ADS storage products is a simple process:  Just pick the desired model(s) from the drop-down list, and specify the number of chambers plus their elevation.  HydroCAD supports the ADS N-12 pipe storage system as well as StormTech chambers.

For pipe or chambers in a stone bed, just describe the shape and dimensions of the outer excavation, plus the stone voids, and the composite storage is calculated automatically.

Technical notes

The HydroCAD definitions for N-12 pipe are based on the published storage-per-foot values listed here.  These volumes are used to calculate an effective inside diameter as used by HydroCAD.  Although the effective ID will differ slightly from the nominal ID, the internal storage calculated by HydroCAD will be exactly the same as the published volume.

The displaced volume is not published, so it is calculated from the outside diameter, minus 30% of the total wall volume which lies outside the corrugations and is available to receive backfill.  (Corrugation percentage based on cross-sectional drawings of the pipe wall.)

For further technical information, read about modeling corrugated plastic pipe.

Detailed product information

For detailed ADS specifications and design information, please visit the ADS web site.

For more information about HydroCAD

Please see the following pages for further HydroCAD information:

    HydroCAD home page
    Pond storage calculations
    Storage chamber modeling  (includes step-by-step instructions)
    Exfiltration calculations
    General support page
    HydroCAD features and capabilities
    Free evaluation program
    Pricing and ordering

N-12 is a registered trademark of ADS Inc.
StormTech is a registered trademark of StormTech Inc.
HydroCAD is a registered trademark of HydroCAD Software Solutions LLC
Product illustrations ADS Inc.


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