TN 6.34-7200 Modeling StormTech Chambers in HydroCAD.

This technical note lists 22 steps to manually model StormTech chambers as a pond in the HydroCAD Stormwater modeling software. HydroCAD can be used to route a hydrograph through a pond.

StormTech chambers are modeled in HydroCAD either using the Chamber Wizard or entered manually. The recommendation is modeling them manually for the best accuracy. When manually modeling the StormTech chambers are placed or “embedded” in a stone envelope. The first step when modeling the chambers is to enter the dimensions of the stone envelope. The stone envelope includes the one foot (min.) stone perimeter around the chambers and the excavation volume around the manifold (if the manifold volume is to be included in the total storage volume).

The steps walk you through opening a new project, how to enter stone envelope dimensions for your detention pond, prismatoid parameters, selecting the StormTech chamber model and end caps. Additional storages and new lines can be defined in a similar manner. Click the OK button to save the pond description. Double-click the pond to view the data for the chamber system. The “Summary” tab contains a report for the overall system including volume of excavation (system only), the volume of the embedded storage, the amount of stone backfill, and the final storage results. Click “Edit” to modify or change any parameters. To analyze the behavior of the chamber system under actual rainfall conditions, create one or more subcatchments (or use in an existing design) and route them into the chamber system.

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. HydroCAD 9.0 has the StormTech SC-310™ and SC-740™ model profiles built into the software. The newer StormTech DC-780™, MC-3500™, and MC-7200™ chambers are available as updates at www.hydrocad.net/stormtech.htm.

Additional details can be found at www.hydrocad.net.