Tassal Tasmanian Salmon, an Australian salmon farming company, backed away from plans to dump treated wastewater from salmon pens into...
Premier community safeguarded with cellular-based system
Most people, not just golfers, recognize the name Pebble Beach, Calif., as one of the premier residential communities in the nation. Nestled on the shoreline and bluffs of the California Monterey peninsula, Pebble Beach is home to hundreds of multimillion-dollar estates and some of the most meticulously maintained golf courses in the world. One course, the Pebble Beach golf links, hosts the annual Pebble Beach Pro/Am golf tournament.
With such high-profile residents and guests enjoying the panoramic vistas of the Pacific and mountains, imagine the environmental and economic losses, not to mention the political uproar, if a sewer spill occurred. The management of the Pebble Beach Community Services District does, as it has demonstrated by maintaining a longstanding record of pump station reliability. However, after a number of recurring communication failures with their phone line based SCADA system, they decided it was time to improve the monitoring reliability of their system.
“From management to the field operators, our district's fiduciary responsibilities concerning collection system operation are the same as any other sewer operators. If we ever had a spill in our service area, the 'beheadings' might be a little more public and spectacular than others, but the result will be the same for any unprepared operator. The Federal and State EPA [U.S. Environmental Protection Agency] mandates are quite clear: no spills. Those kind of press conferences are unacceptable to our board members,” said Frank Rose, district maintenance manager for the Pebble Beach Community Services District.
With construction mishaps, fiber upgrades and normal maintenance, more and more “copper” phone line services (dedicated or dial-up) are subject to interruptions. Factor in the economizing that most local telephone companies are being forced into, and hour-long problems are turning into days. Couple this with a “zero-tolerance” by district managers and the EPA, and redundancy starts to become standard operating procedure.
Weighing the Options
“Our initial logic was pretty straightforward. We have two or more pumps at every lift station for redundancy. We all know that any machine (or system) can break for a variety of reasons. Why not extend that type of safeguard to the monitoring and control system,” Rose said. But at what cost?
The district looked at the feasibility for both licensed and unlicensed (spread spectrum), radio-based SCADA monitoring systems. The upfront costs were high and integration of the two systems appeared difficult. Additionally, through conversations with other radio-based SCADA users, questions arose about the true reliability and ongoing maintenance issues of such a system.
“There were a number of times we felt we would be creating more problems than we'd be solving,” Rose said. “The final straw was the anticipated resident reactions to YAGI antennas and their pole masts sticking up in the air at the lift stations on the golf courses; it just wasn't going to fly.”
The Best Solution
A few months later, the district was given a demonstration of the Mission Communications cellular-based SCADA/monitoring system by Dave Nemiroff of Nemiroff, Monahan & Associates, a consulting engineer to the district. “I had read about the Mission system in trade magazines, but because of the low price and my prior experiences with cellular, I really didn't think the system would meet our expectations. But my customer seemed to be at an impasse, so I arranged a demo,” Nimeroff said. “We were downright amazed at the capabilities and simplicity of the system. If it worked as advertised, we felt we had a solution.”
A trial installation was agreed upon.
The initial trial unit in Pebble Beach was installed on a submersible duplex pump station housed in an underground vault. The Mission system monitors AC failure, high level, low level, phase loss (through a phase monitor) and two pump runtimes. The RTU was installed with a Mission-supplied low profile, attack resistant, antenna. This was done to respect the district's desire to minimize public exposure to any antennas.
“After the unit was first installed, we got a phone call from Mission's Technical Support Group. They had detected through their diagnostics that the trial unit had poor cellular signal strength and was occasionally going off-line,” Nemiroff said. “I decided to look at the installation in depth and found that the installer had taken the district's instructions on “hidden from view” antennas a little far. The antenna had actually been mounted below ground in the lift station access vault. I was surprised the RTU worked at all—it was like trying to use a cell phone from a sub-basement elevator.”
After the initial confusion over antenna placement, the trial went smoothly and the district subsequently installed RTUs on all eight of its lift stations. Soon thereafter, the district ordered more RTUs to monitor the flow to the wastewater interceptor line, and to monitor levels at their water storage tank.
“We were extremely pleased with the system's performance so we started to take advantage of some of the other capabilities it offered. We bought Mission as a backup to our existing SCADA. In many areas it outperforms the primary system. It's certainly a heck of a lot less expensive and easier to use,” Rose said.