# Modeling stormwater gate valve open and closure controls

 Product(s): SewerGEMS, CivilStorm Version(s): V8i, CONNECT Edition Area: Modeling

# Problem

How do I model a gate valve opening and closing based on a logic such as pressure at a pressure transducer (water level in an upstream manhole for example) or based on time (for example open a penstock after a storm).

# Solution

This can be done using the Explicit (SWMM) numerical solver (selected in your calculation options) with SWMM Control Sets. After selecting the SWMM solver, define a start control structure on your downstream conduit such as an orifice with a particular label that will be referenced in the SWMM controls.

Next, Go to Components > SWMM Extensions > Controls sets. In here you will need to define two control rules; one to set the setting of the orifice to 0 when the level reaches the point when the gate should close, and another to set the setting to 1 when the orifice should be fully open. For example:

RULE A

IF NODE WW-1 DEPTH <= 0.1
THEN ORIFICE OR SETTING = 0}

RULE B
IF NODE WW-1 DEPTH > 3
THEN ORIFICE OR SETTING = 1

• You can read more about SWMM control syntax in the Help or in the EPA-SWMM documentation
• Time based controls can also be used (see article below for more)
• You may need to use a wetwell upstream instead of a manhole for storage.
• For orifice and weir controls, a conduit control structure needs to be used. If you are modeling an outlet structure of a pond, you will need to select "no" for the pond outlet structure's "has control structure" and model a start control structure on the conduit downstream of the pond outlet node.
• If using metric units, some versions of the program still require the depths in the control sets to be entered in feet.
• In at least one previous case, high continuity error was seen. The continuity error was much better if the gate wasn't opened all the way (80% versus 100%). In this case, try enlarging the full orifice diameter
to compensate. You may be able to further reduce the continuity error by reducing the routing timestep.

Example: a penstock/gate in a pond starts closed and opens up after a storm event, to let the pond's water into the storm drain system:

Example model for the above (need version 10.02.XX.XX or greater to open):

Pond gate penstock SWMM controls.zip