Modeling StormTech Chambers in Hydraflow Hydrographs.

This technical note provides the steps for modeling StormTech chambers as a pond in the Hydraflow Hydrographs modeling software.

StormTech chambers are modeled in HydraFlow Hydrographs using either the “Manual” input option or the “Chambers”

input option. The manual input option requires the use of the StormTech Cumulative Storages spreadsheet to calculate the stage storage data. Data points are then copied from the Cumulative Storage spreadsheet into the Manual inputs options menu when creating a pond in HydraFlow Hydrographs. The second option of using the “Chambers” input in HydraFlow is recommended as it makes it easier for the user to modify pond size when designing the outlet controls.

Data inputs are found under the Stage/Storage/Discharge setup screen. When the “Chambers” option is selected, the parameters can be set by invert elevation and shape. The Rise, Span, & Barrel Length should follow the values in the provided table.

Two layout examples are included. Example 1 is a simple rectangular shape that contains 152 MC-3500 chambers in 8 rows (16 end caps), and model 156 chambers (the 16 end caps convert to approximately 4 additional chambers). Drawings will show the dimensions assuming minimum spacing and offsets for the stone perimeter specified for an MC-3500 chamber.

Example 2 accounts for the addition of manifolds, an irregular shape, and the inclusion of perimeter stone for an MC-3500 chamber. Both examples feature Imperial units and calculations used in site planning. With added complexity, the addition of manifold offsets, and inclusion of perimeter stone, the Hydraflow outputs can have a higher percent deviation than that shown in Example 1, with a percentage difference of 1.0%.

This document does not address setting up a hydrograph or connecting inlet and outlet devices. This document is for the sole purpose of modeling the chamber stage-storage volume.