Concrete Stormwater Chambers
HydroCAD provides direct support for concrete stormwater chambers, such as those manufactured by
members of the Northeast
Precast Concrete Association (NEPCA).
This allows concrete chambers to be easily used within any HydroCAD model for
stormwater storage, detention, or infiltration. HydroCAD also includes
an interactive chamber
wizard, which greatly simplifies the layout, pricing, and modeling of
underground storage systems.
chamber definitions are included in HydroCAD 9.0 and later, plus an interactive
chamber wizard for easy layout, pricing, and modeling of underground storage
program update is required to model NEPCA products in
Important: In the HydroCAD
chamber library, the previous chamber definitions for Galley and Dry
Well are now grouped together under "Concrete". Chamber
definitions for concrete pipe and Crown-Span will be found under "RCP".
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
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 8.5 also allows for the
wall thickness of the chamber, so that the correct storage (stone plus chamber)
can be determined at any elevation.
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.
Using Concrete stormwater chambers
Setting up a pond to use concrete storage chambers is a simple process:
For a square chamber, pick the "prismatic" shape and enter the required
dimensions, including the wall thickness. For special shapes, such as a
leaching chamber, galley, or arch, pick "Prefab Chamber" and select the desired model from the
drop-down list. Pipe storage can be modeled by selecting a "horizontal
cylinder". After the selecting the desired shape or model, enter the chamber elevation and
the number of chambers.
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. This includes an allowance for wall thickness,
even when the thickness varies at different parts of the chamber. Or you
can use the new chamber wizard for automatic
chamber layout, modeling, and cost estimating.
Detailed chamber information
The pre-installed chamber definitions are based on common industry designs,
as manufactured by
United Concrete Products, and others.
For more information about HydroCAD
Please see the following pages for further HydroCAD information:
Pond storage calculations
Storage chamber modeling
General support page
HydroCAD features and capabilities
Free evaluation program
Pricing and ordering
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