Have you encountered these green cages in East Sacramento and wondered what they are? Who put them there? And why?

The cages protect an important part of the transmission water main system: air release valves. Over time, tiny air bubbles in water will collect and eventually form large bubbles which get trapped in high points within the water mains.

These devices allow the air to escape. If the air was allowed to remain, the air would eventually build up and begin restricting flow through the water main, eventually impacting the City’s ability to move water through the mains. The devices were recently installed in East Sacramento when the Department of Utilities placed a new transmission main in the area.

Although air release valves may not have been noticed before, there are over 600 of these devices all around the City. A number of years ago, the regulations allowed for these devices to be installed in manholes when proper drainage was available, so the majority of them were installed within the street section below grade.

GreenCages

However, due to a change in the state regulations, all devices must now be installed above grade and above the 100-year flood plain. This regulation applies to any new air release valves that is installed, or any existing air release valves that is removed for maintenance or replacement. As existing air release valves are brought up to current standard, more of these cages will become noticeable.

Find more information about the City’s water main pipeline and meter projects.