HydroCAD Stormwater Modeling - Since 1986

NDS-StormChamber supported by HydroCAD

HydroCAD provides direct support for the NDS-StormChamber system, allowing the StormChamber to be easily used within any HydroCAD model for stormwater storage, detention, or infiltration.

HydroCAD also provides an interactive chamber wizard for easy layout, pricing, and modeling of underground storage systems.

Note: With the completion of the StormChamber acquisition by NDS, the StormChamber chamber definitions have been renamed to NDS StormChamber.  Previous projects will continue to work exactly as before, but new designs will use the new naming system.  To get the latest StormChamber definitions make sure you're using HydroCAD-10.2.  If you have an earlier version of HydroCAD, you must obtain a program update to get the latest StormChamber support.

Note: Depending on your release, you will find the StormChamber listed under "NDS", "NDS-Stormchamber", "StormChamber" or "Hydrologic Solutions" 

How chambers are modeled

In a HydroCAD model, stormwater chambers typically appear as part of the storage definition for a "pond".  In the simplest case, HydroCAD calculates the available storage for use with other calculations.  But more often, it is used to generate a complete inflow or runoff hydrograph and route it 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 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 crushed 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.

HydroCAD can also model almost any imaginable storage arrangement, including 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.

Modeling with the StormChamber

Setting up a pond with StormChamber storage is a simple process:  Just pick the StormChamber model from the drop-down list, and specify the number of chambers plus their elevation.

For chambers in a stone bed, you can describe the shape and dimensions of the outer excavation, plus the stone voids (porosity), and the composite storage is calculated automatically.  Or you can use the new chamber wizard for automatic chamber layout, modeling, and cost estimating.

Modeling the StormChamber SedimenTrap

Each StormChamber installation is normally configured with two "sediment traps".  If desired, the volume of the sediment traps can be included in the HydroCAD model by using the "vertical cylinder" storage option with these parameters:

Diameter=2.50'   Height=1.67'  Side-Z=0  Embed Inside=Nothing  Storage Multiplier=2  Voids=100%

Set the storage invert elevation 1.67' below the bottom of the StormChambers.  The option to "Allow Exfiltration" should not be selected, since exfiltration for this area is already being allowed for the main chamber system and should not be double-counted.

Detailed chamber information

For detailed chamber specifications and design information, please visit Hydrologic Solutions.

For more information about HydroCAD

Please see the following pages for further HydroCAD information:

    Pond storage calculations
    Storage chamber modeling
    Exfiltration calculations
    General support page
    HydroCAD features and capabilities
    Free evaluation program
    Pricing and ordering

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