A new floating early warning alarm system in manholes helped the City’s Department of Environmental Services (ENV) prevent more wastewater overflows during last weekend’s storm that dumped double-digit rainfall figures on various parts of Oahu.
On Dec. 11, ENV’s Collection System Maintenance Division (CSM) received 51 trouble calls, including 18 early alert alarms at various times signaling rising wastewater levels. Crews were dispatched immediately after each alert and able to thwart 12 of the potential 18 overflows at manholes with the device.
“This unique monitoring system allows us greater insight and intelligence gathering information on what is transpiring in our collection system,” Eric Takamura, director of ENV, said.
During the past 18 months, ENV installed 131 floatation monitors at all of its key manhole locations in its collection system, either at the lowest points or in areas with a history of overflows.
The instruments are the product of Utility Systems, Science and Software, Inc. (US3), which was founded in 2002 and headquartered in Santa Ana, Calif., and Service and Engineering Facilities in San Diego, Sacramento, Salinas, Calif., and Knoxville, Tenn.
The manhole lids are a unique solar panel that charges by sunlight. On the other side, a monitor dangles to a particular depth from a communications box. Once wastewater rises to a set level, it triggers an alarm via text message to ENV’s field service supervisor. The message includes the exact address, which allows the supervisor to dispatch a crew immediately to the site.
“When this system is functioning during normal weather conditions, we are able to remedy the situation with 95 percent effectiveness,” Takamura stated.
US3 provides simple, cost effective, wireless Monitoring & Event Notification. This information can be sent to cell phones, pagers, work/home phones and/or emails in approximately 800ms. ENV crews can also monitor the affected area on the internet.
As a precautionary measure, the supervisor will dispatch a crew to the exact location where they may be able to unclog the pipe before it results in an overflow.
Honolulu is only one of a handful of areas in the country that use this proactive device.